Football is a money game.
Everyone accepts this, and for owners of clubs not bankrolled by entire countries it can be difficult sometimes. It's understandably tempting when you are offered big money for a player you've brought in cheap and nurtured them to becoming a top talent.
Newcastle United currently find themselves in this exact situation with captain Jamaal Lascelles, but no matter how appealing the quick cash-in might seem, fans and pundits alike must implore Mike Ashley to refrain from such a deal.
Right now, the Magpies cannot afford to sell one of their star performers. To be honest, there are few in the Tyneside club's first team they could allow to leave.
After a remarkable job re-establishing the club in the Premier League following last season's promotion, Rafa Benitez has a job of major squad improvement - whilst a harsh criticism, there was still some truth to the rhetoric that Newcastle played the season just gone with a Championship squad.
That improvement is an impossible task if, just as he strengthens the areas that needed improvement this season, he finds the rug swept from under his feet in one of the few areas already strong.
Centre back was one of the few positions in the squad that Newcastle could be genuinely pleased with.
Lascelles has been immense at the back for the Magpies this season, and following the introduction of the confident and communicative Dubravka behind them, Florian Lejeune really came into his own too.
Even in reserve, Ciaran Clark is a perfect Premier League backup and Chancel Mbemba - while Benitez does not trust him and will likely look to sell him this summer - has the talent to cover if called upon should he still be at St. James' Park next season.
Finally, to the delight of Newcastle fans, there was one position in the side that we didn't feel we had to demand improvements in. With Dubravka's signing now permanent, the core foundation of our team, the central defensive unit, was very promising.
Yet, with a single flick of the wrist, Ashley could bring all that crumbling down around him.
He simply cannot be tempted to cash-in on Lascelles, or allow clubs to begin negotiations with the English defender. If they do, then Newcastle seriously risk losing him and that would be disastrous for the club.
Yes, the deal would provide the club with a brilliant pot of funds that, in a perfect world, could be directly reinvested into the squad.
However, this is Newcastle United.
The club would likely never see the whole sum of Lascelles' transfer given back to the transfer kitty, and even if it was, with the extortionate prices players are demanding these days the only way we could do more than simply replace what we'd lost would be to shop abroad and bring in young, untested talent.
That's a gamble at best, and still doesn't address the other issue we'd lose in Lascelles - not just a talented central defender, but a captain and an influential and commanding figure in the dressing room.
No matter how much money is put on the table by the clubs interested, Newcastle can't afford to take it because we simply can't replace those qualities we would lose in Lascelles in the current financial climate of football.
And Newcastle fans have reason to fear it happening too, because the club has a track record of this kind of deal. It was a hallmark of the Alan Pardew and Steve McClaren eras in particular, to buy cheap and sell on for profit.
Sure, most of those players were shipped across in bulk from France, and the majority failed to make any kind of impact or profit. Benitez and the club are still only now getting to the end of the backlog from the required clear-out from that system.
But, there were some gems that came across too. Mathieu Debuchy and Yohan Cabaye probably stand as the two most egregious examples of cashing in on talented players.
Debuchy was signed in January 2013 and it was clear he was a talented full back that could help the team push on.
Fast-forward 18 months and a big money bid - at least at the time and for Newcastle - of £12m and he was on his way to Arsenal and Newcastle had to strengthen all over again.
However, the Debuchy situation is nowhere near as clear a cash-in as was the case with Yohan Cabaye.
The Frenchman was instrumental to some of the best seasons in recent years for Newcastle, including most notably the fifth-place finish in his very first season at the club.
There the Magpies narrowly missed out on Champions League football on the final day, and it looked clear the club had unearthed a real talent to help them reach lofty heights.
Despite poorer finishes in seasons to follow, Cabaye continued to impress and demonstrate a level of quality that was a cut above the usual Newcastle players - much like Lascelles has done recently. He quickly wrote himself into being a fan favourite.
So, naturally as Newcastle do, the club willingly accepted when Paris Saint-Germain came knocking with a massive £19m bid, with add-ons.
The Magpies saw one of their best players sold on for a quick profit - one that was not successfully reinvested into the squad.
There are times to take massive cash-ins on players, and Newcastle have done well at this in recent times too - think the combined £55m the club got for Moussa Sissoko and Georginio Wijnaldum - but with now is definitively not the right time.
It won't make any difference to Ashley's thoughts, but fans and pundits alike need to reinforce that message to him.
It's a simple instruction - do not, under any circumstances, sell Lascelles this summer.
Should he listen, then the club can strengthen and push on. Should he not, there is a serious risk of Championship football once again gracing St. James' Park sooner than anyone would hope.