The potential awardable events --- baskets sunk in a game, multiplied by their value (1, 2, or 3 points per basket) --- is finite and bounded. But should there ever be a means to score more baskets, the points will be there.
You seem to be confusing awardable events (baskets) with points (numbers from the set of all positive integers). It's the latter which are infinite.
Put another way, even if the total number of baskets scored in all games for all time has some finite maximum, by changing the awarded points per basket the total points in a game could increase.
Rather than 1, 2, and 3 points we might award 2, 4, and 6.
Or 10, 20, and 30.
Or 1*10^100, 2*10^100, and 3*10^100.
There are always more points available to match to baskets and their value. There is no "point store" that can be depleted.
(I'm not arguing that awarding a googol points per free-throw is desirable or would improve the game. I'm saying it's possible to set the scoring to do this. Pinball games seem to follow a similar scoring logic, for comparison.)