Of course it is. Sometimes.
If withholding something you could otherwise freely give injures another, that’s hardly an act of generosity.
But if you build something that pleases only you, that’s a selfish act in a good way.
The first example is a dead end street, the second can become a generous sharing act.
If you build the world’s most magnificent high-end audio system and every aspect is handpicked just for your pleasure, imagine how many like-minded people would love to share your personal pleasure.
The fact you selfishly created a masterpiece reflecting only your values is priceless. A work of art, not a dead end street.
Go! Build it! Put together an audio system just for you!
Then share it with the world.