The World Bank periodically adjusts the threshold upwards for this reason. In 1990, they used $1/day. In 2008, they adjusted it to $1.25/day. Now they are adjusting it to $1.90/day.
You're two random people on the Internet.
I'm siding with the World Bank, not with the internet commenter who demands another internet commenter defend experts.
You're the one making the extraordinary claim here.
It's possible that they are failing to adjust for inflation sufficiently, but that claim needs support. How much inflation was there between 1990 and 2015? Why does it differ from their calculation?
http://www.usinflationcalculator.com/
http://www.westegg.com/inflation/infl.cgi
Of course, if you live in Venezuela, things are different, but World Bank uses US$.
edit: only now noticed that this was mentioned already in an earlier comment by oblio.