Exactly morality is a social construct.
Ah, the classic "x is a social construction". Edgelord 101.
This is a meaningless distinction. The fact that something is a social construct doesn't eliminate consequences or make that something unimportant. There's no value to actually stating the obvious. Now if you can come up with an actual argument for how piracy isn't theft, I'd love to hear it.
It is, but there is no imperative for you to act in the right way. Is/ought gap etc.
Would you steal from a retail store? If not, why not?
In most cases, it's imperative to follow societal morality to avoid negative consequences, now the chance of getting in legal trouble over pirating GTAV is incredible low, yes, but that's beside the point. Potentially it would be incredibly easy to get away with mugging someone in a dark alley at night (wear a mask, etc), taking all their cash and using it for booze, but most people aren't doing that. I wonder why.
The line of logic you're using promotes degeneracy, why not mug someone in a dark alley at night? Why not steal someone's identity and use it to take out a loan or empty their bank account? They'll probably get reimbursed anyways.