I’d say in your case piracy was 1000% justified. You bought it, you should be able to play it.
I think piracy is acceptable if one of these two conditions are met:
- You already own a copy of the game
- The game is no longer sold as new, such that any legitimate copy would have to be secondhand.
Someone actually emailed Valve about this back in 2013. Here’s their response: https://i.imgur.com/4sa1Ln6.jpg
It seems like Valve wants us to think they have an EoL plan. With the goodwill they’ve built over the years, I want to believe them.