It’s important to think about the counterargument, I agree.
To counter your counterargument: it’s not a good argument on many levels (scope, allocation, distribution mechanism, effect). The main reason is that this sort of charity doesn’t improve the core problem of low(er) social mobility. The opportunity to pursue self-development/self-fulfillment should not be tied to the whimsical act of a better-off person but presented to everyone as equal as possible - through common goods and services. The impossible future is impossible due to vastly different prerequisites. The person’s “greatness” will never be seen, as most likely they will never be presented with the opportunity to display it.