Hm. FInding people free at the same time and with the money spare and so on to go with you places can be tricky.
I've stayed in hotels and things alone and to some degree travelled alone. It was OK.
It wasn't intended as a holiday though. One time it was because I was intending to move to Malta and the other time was an intention to move up north here in the UK. Both times I came back relatively quickly! There have been some more smaller trips I think.
I've never tried a holiday alone, specifically. Is it any good? I can imagine it being nice, but just not quite as good as with others, which is what I experienced when I was on my little adventures!