Thanos knew: I think We all have seen Avengers infinity war
Thanos knew: and we all were extremely shocked when we saw that scene
in which Thanos suddenly called thinking that how Tony stark and we all surprised
and started thinking how Thanos could know Iron Man.
We all were surprised because we didn’t think even for a one moment
that Thanos knows tony stark actually, I mean literally every one of us had Goosebumps
when Thanos said Tony Stark and the Iron Man as in the response of this asked
if Thanos knew him and then Thanos replied
you are not the only one who cursed with knowledge.
Wow, God knows how many hidden meanings such this line must have!
This question answered by Joe Russo and Anthony Russo altogether
in one of the conferences that Thanos knew Iron Man as the person
who destroyed his plans of acquiring Space stone and capturing Earth with the help of Loki.
and his army and because of which Thanos was anger
and wanted to know that
who destroyed his plans and hence he got to know about Tony Stark as the person
who shattered all his hopes and dreams as he got clear that
Iron Man was the one who took the missile launched by SHIELD
through the portal and destroyed the entire ship and the power of Thanos
ultimately by killing all the army of Thanos and hence destroying the whole plan of Thanos.
by this all we come to know that Thanos was afraid of tony stark and his power
but he was afraid too that he will destroy his kingdom of power.
And this is the only reason that Thanos knew Tony stark in Infinity wars
and we got a chance of listening to one of the most
confusing, intense, and mysterious dialogues of the movie at all.