Knowing the limits before the first spin
Choosing your bet decides what each spin costs, not when the bonus round arrives. How often the free spins come is not known in advance, and the screen gives no way to work it out. The result of one session is random, whatever the RTP shows. Two players with the same bet can end one session far apart.
Checking the RTP before you play means reading the game rules, because the version running in this lobby is shown only there. The three versions differ slightly in the return on each stake over time. Spins on the screen do not show which one is active.
Deciding how much the top prize should weigh in your choice starts with the number: the maximum win is 25,000 times the bet. That ceiling is reached very rarely, so the figure describes the limit, not the usual result. Set your budget before the first spin, not after a big win.