some Delta captains' were supposedly making approx up to $500,000
per year

Since such a statement is not an opinion, but simply a question of
fact, then it's an inarguable as such.

I do not know what the pay is:

I recall reading the $500,000 figure in a newspaper, and I thought it
rather high, but it wasn't discussed (specifically/exactly) during
their pilot strike not long ago. I recall I also have read that some
starting-out airline pilots at Atlantic Southeast (?) are getting circa
$50,000 more or less.