If you do something that turns out wrong, you can almost always put it right, get revenge, get over it, learn from it or at least deny it. But once you’ve missed out on something, it’s gone.
There will be the band you never got to see live, the winning streak you never got to cheer on, the brilliant retiring professor whose course you never took, the relative you never got very close to. It’s a long list no matter what. Try to keep it as short as possible.