Zero investment? At work we pretty much exclusively use GCC and Clang/LLVM, so I use them EVERY DAY except when I'm on vacation (which I'm just back from, sure could have done with a few more weeks boss!).
Wth does Linux never changing come from? I'm sure it's the fastest developing kernel out there bar none. If you are alluding to it changing from GPL (as you brought it up in conjunction) then that's probably as likely as Microsoft GPL licencing Windows.
Bottom line, GCC and Clang/LLVM are great compiler toolchains, they have different strengths/weaknesses. They are both also developed at a very high pace, something which is likely fueled by the competition they offer eachother. This is awesome for all of us using these compiler toolchains, no matter if we use both or just one of them.
There are zelots on each side of the fence (you are one of them) who refuse to acknowledge that they both offer great value and instead try to discredit the one they don't like as toy/bloated/slow crap/etc etc, in my opinion the reasons for these attacks generally have nothing to do with the compilers themselves but are rather results of some zelots identifying them as GPL vs BSD and not being able to look past that.