Getting patent is fucking expensive, also it is afaik region-limited. You can get your patent for say EU, you need lawyers and lot of money for that, and if you would like to extend that to US, you need new lawyers and more money.
So it is out of realm of what's possible for normal person.
It's not that expensive in the US. A few hundred is typical, and you don't need a lawyer (though spending the money on one up front will save you from spending more when you screw it up the first few times).
Don't you need working prototype to get a patent? Otherwise musk or bezos or another for-profit asshole could patent every known scifi gimmick, wait until someone actually invents it and then send him a bill...?
If a prototype is requires, only people with wealth could afford to produce a working prototype without revealing their invention to investors and without risk of the idea being stolen...