It really depends on the context.
If someone is happily independently living alone, without complaint, enjoying their solitude, not wanting anything more, and a rando stranger comes along and opines that they should get out more, then yes, that is a bit patronizing.
However, if someone indicates that, despite enjoying their solitude, they do also want more friends, more experiences, more opportunities, etc, then "getting out more" is kinda essential to doing so, and is fairly sensible advice - with it understood that neither staying home nor going out are a "waste of life", but that if you want those things which are not readily found at home, "going out more" is probably a reasonably unavoidable component to making those things happen.