This isn't true. It took me two seconds to create a new project, run `cargo build` followed by `ls -hl ./target/debug/helloworld`. That tells me it's 438K, not 3.7MB.
Also, this is a debug build, one that contains debug symbols to help with debugging. Release builds would be configured to strip them, and a release binary of hello world clocks in at 343K. And for people who want even smaller binaries, they can follow the instructions at https://github.com/johnthagen/min-sized-rust.
Older Rust versions used to include more debug symbols in the build, but they're now stripped out by default.
rustc 1.84.1 e71f9a9a9 2025-01-27 -rwxr-xr-x 1 user user 9.1M hello
So 9.1 MB on my machine. And as I pointed out in a comment below, your release binary of 440k is still larger than necessary by a factor 2000x or so.
Windows 95 came on 13x 3.5" floppies, so 22MB. The rust compiler package takes up 240mb on my machine. That means rust is about 10x larger than a fully functional desktop OS from 30 years ago.