But once they have the patent they can license it to others, this denies them the chance. The point being that the idea may die with the person rather then ever being known in the first place if filing is too big a burden.

My understanding is you have to regularly pay to keep a patent valid until expiry, but I could be mistaken. Varies by country I’m sure.

I agree with your premise that it’s better that someone with intent use it, but it’s not that black and white.