Up to over a million chips now[1], but a still 10th. 5 fewer left in though: just 40 of us left

[1] Dealt Ah4h in the small blind, called a 100k raise from the other bigstack at our table.

Ten-high flop had 2 hearts, a 2 and a 5, giving the nut flush draw, a gutshot straight draw, and a chance of pairing the ace. So I opened for a quarter mill. He folded.

Wonder what he had to have made the preflop raise and then fold in position on the flop?