If Tsitsipas really thinks that, then he really IS just a pretty face. Such a superficial choice. Plus, who wants to be known as a Slamless #1? Fiero mentioned just the other day that Dinara Safina was one, and that was 14 years ago. Ignominious legacy, around these parts. Rios was also a slamless #1, IIRC.
Rune has the right idea. As Rafa always said, and I believe he meant this earnestly (at least most of the time,) he didn't care about #1. Get the results, and the #1 will take care of itself. It's the better attitude, IMO.
There is a lot of truth in this. I'd already forgotten that Coric won Cincy last year, (forgive me, as he is your fellow Croat,) and I pay a lot of attention. Sinner winning in Toronto is a big deal for him. A 1000 is a great title, and considered a "Big Title," as they often seem to be laid out these days. However, from what I can tell, everyone feels it's a stepping stone for Sinner. If he doesn't win a Slam, there will be disappointment.