The 90s weren't great. We had wars in Yugoslavia, Chechnya, and more.

But, in general, I do have a sense it was a uniquely optimistic decade for many people in the former First World, mainly because the Cold War ended and there was a sense that we had "won". Western Europe in particular demilitarized a lot as a result, the EU was formalized, the Good Friday Agreement was signed, Oslo Accords happened, end of apartheid etc.

For Americans I think 9/11 derailed things again.

Outside of the former First World, I'm not sure they'd see the 90s the same way.

It was nearly a golden age in indochina. People in countries like Malaysia, Indonesia, (South) Korea, Thailand, Taiwan, etc experienced incredible and permanent improvement in living standards

but yeah it wasn't that great anywhere south of cancun or cairo