Casinos might choose to give you a free spin or bonus based on your commitment and how frequently you gamble in their casino. However, your tier also depends on how often, you will get bonuses from the casino.
this is beneficial for the gambler but ultimately still beneficial to the casino as well because with a free spin or a bonus you will just spend your money on their platform again
Some casinos, when you are in the VIP tier, at the end of the week, they give you back some percentage from your losses, so that you can gamble and wouldn't feel your losses that much.
as i have read before how this percentage will just be spent by you making another bet so at the end it is still really the casino that wins even if you get a little bit out of it or better yet you win on a lottery