Depends on the Haz-Mat load.
I drove truck and had my doubles/triples; haz-mat; and tanker endorsements. Which meant I could haul anything. Some military explosive cargo can pay well, but it is a pain to have an armed escort both in the truck and behind you. Planned routes, with timed rest stops and so forth. No thanks. It wasn't worth it.
I started hauling "specialized" which is basically all your oversized loads, that is when I seen my bank account start adding up. $140,000 the first year. But I did work my butt off, 5 weeks out and 2 days home.
As for the Haz-Mat, if you haul explosives it can pay pretty good, so can some nuclear waste loads, however, you are bound by stringent time restraints and many times armed escorts to deal with.
Other Haz-Mat loads are not worth hauling. Better off with "specialized" If you get a cargo loader haul out of Florida it pays $4 per mile plus fuel surcharge plus permits. I paid off half of my truck payment with one trip to British Columbia.