Say the same thing about seatbelts in a car. If you don’t plan to have accidents, why do you need seatbelts?
Car accidents, like mistakes in programming are a risk that has a likelyhood that is non-zero. A seatbelt might be a little bit annoying when things go well, but much less so when they don’t. Rust is there to stop you in most cases when you try to accidentally shot yourself into the leg, unless you deliberately without knowing what you are doing while yelling “hold my beer” (unsafe). And contrary to popular belief even in unsafe blocks many of Rust’s safety guarantees hold, just not all
If the net benefit of a ownership concept like Rust has it is high enough, this ahouls be an easy choice for rational actors to take. The odds are on Rust’s side here, because humans make mistakes and if Rust manages to allow productivity despite stopping certain classes of these mistakes, there will be a net benefit.
Just like with the seatbelt, there will be always those that don’t wear one for their very subjective reasons (e.g. because of edge cases where a seatbelt could trap you in a burning car, or because it is not cool, or because they hate the feeling and think accidents only happen to people who can’t drive).
I write Rust for a year now, and I constantly see bugs far better programmers made in say C++ where Rust just wouldn’t allow you to not handle it. E.g. Crashing your software by writing to a file that is locked by another process. In Rust this would mean the deliberate act of ignoring a Result, unwrapping it and moving on. You can ignore it, and Rust will crash, but you know exactly where you took that risk.
Things like these remove a lot of cognitive load from the programmer which can be put into more pressing topics