The issue is -not- about it being a scam. It’s about actual laws about gambling.
What you are saying here is still gambling and illegal/against the TOS of patreon.
The options given earlier in the thread, in an official post from Patreon itself on the criteria and how to go about adding giveaway type things to your account, is pretty straightforward on what you can and cannot do.
https://blog.patreon.com/patreons-stance-on-raffles-lotteries-and-giveaways
This is also a topic talked about a lot on here. Here is a previous topic about giveaways and some other options given by staff while discussing options with creators. Raffle Replacement
There are more if you use the search function for “raffles” “giveaways” etc.