It's becoming Californiaized, there is also a lot of tech bros moving to Denver. A similar thing is happening in Texas. There is lots of ski resorts and outdoor recreation, which brings in lots of eco friendly types.
You’re right, but there are counter trends in Texas that seem to be favoring Republicans much more (Conservatives from CA moving in as well and not just techbros, Hispanic trends especially in the RGV, Houston and maybe SA potentially being maxed out for Dems.)
Colorado may have some similar trends but they aren’t as consequential in favor of the Republicans, partially because Texas is way larger than Colorado.