Its interesting - the salary cap comes into play as well - but this article (and the parent article which is a bit more detailed into the tennis aspect itself) basically summarizes to 'top tennis players can use outsized prize winnings to hire top staff to extend their dominance'.

At the root - surely the same is true - top paid footballers likely pay (themselves or through the team) for top staff (physio, coaches, trainers) except substituting the resulting extension of dominance for whatever happens in that particular sport; whether growing older is more or less of a cost than in tennis.

What is interesting is that in a team sport, the money that Real Madrid makes is probably enough to hire top staff, which then applies to the whole team. (Players themselves may go above and beyond that.)

In tennis (simplifying) - there is no team, Federer gets all the money, Federer reinvests what he deems necessary into his own continued performance, expecting outsized benefits.

Now if the only benefit gained from being at the top is money, all that is necessary is outside funding of some sort to help punch your way into, and to extend your stay in the top 100. Would be curious if the two under 25s now dominating the scene are doing so on physicality, money, or more likely a blend of the two.

Essentially the article sort of describes the precarious-ness of being a top ~1000 player, having a very narrow period of time before finances fun out, or you age out (without the proper support structure, ex. get injured), before you start making the money necessary to fund staying in the sport at a high level. And I guess the argument is the sport would be more fair and balanced if ex. everyone who entered the top 1000 were able to get access to the support that the top 100 (or 10 as mentioned) have.