Points expire. Some programmes wipe the whole balance after a few months without play, others expire each point a fixed time after it was earned, and a few reset everything once a year. A balance left to build toward a larger reward can vanish before it gets there. Checking the expiry rule when joining, and redeeming small amounts regularly where the rules allow, keeps the points from turning into a number that pays nothing.
Stakes made with bonus funds often earn no points at all, or earn them at a reduced rate, and the loyalty terms say which. The account page usually shows the current balance and the points still needed for the next reward, although the conversion rate may sit elsewhere. A quick note of the balance before and after a session shows the earning rate in practice, which is a useful check on the published one.
Points are earned per amount staked, and the rate usually depends on the game. Slots tend to earn the most, while table games and live games earn a fraction as much, because their lower edge leaves the casino less margin to share. A typical rate might give one point for every ten units staked on slots. The earning table sits in the loyalty terms, and it decides which games actually feed the balance.