Hobbyists create new languages because it’s fun, or in the earlier stages they think they can make something better than existing languages.

Big companies / orgs have made new languages like Swift, Kotlin, TypeScript, Elm, Rust, Zig, Elixir because the previous counterparts (Objective C, Java, JavaScript, also JavaScript, C++, C, Erlang) have big flaws.

Everyone still creates DSLs because they are more effective at solving certain problems than general-purpose languages.