Or maybe none of that matters at all, since we all die alone one way or another, it's the journey and not the destination. Life is to be lived, experienced, and one could argue dying abruptly in aggressive pursuit of your dreams is ideal.
There's a common saying that you can't take your stuff with you when you die, but you can't take your memories or relationships either.
There's plenty of reasons to cultivate relationships in the present moment without justifying it by anticipating regret on your deathbed if you don't.
And there's plenty of reasons to spend this life enjoying time with yourself.
There are lessons you can learn only in deep relationships and lessons you can learn only through extended time by yourself.
I wouldn't be prepared to call a life lived in isolation and in harmony with nature a regretful life at all.
The only thing of value we leave behind is our artistic creations. Whatever Javascript adware or trendy C replacement you're hacking on will be obsolete before you finish decomposing. All your "experiential purchases" like travel, relationships, etc. will be gone in a flash. The only thing left will be the art you created. The art you created is of course not entirely your own, it's essentially a restatement of the world cultural traditions, but through the lens of your life experience in a way that only you could create.