It's a matter of scale. At level 29 in hunting skills and lvl 20 paramedic/evade, i tested out ultra-eco hunting for about a 10 runs. In the first few runs, I was getting a consistent 200-400% return using no armor, no fap, no amp, and the opalo vs chirpies while the fragments were 1 ped each. However, it took about an hour to use 20 ped of ammo. Then I switched to the m3a + a101 vs provider-guardian snables, and I was consistently making 150% returns for over a week. So, at his level with his equipment, he's doing the same thing but with bigger monsters.
However, the main point of contention I have is that anyone who started before 2007 has a huge advantage over anyone else because they were able to get stuff that doesn't drop anymore, like imp/mod faps. While anyone could do what he did, they would have to deposit $50k. He didn't have to deposit 50k, he used the 50k of profit he made already. For example, he could get an imp or mod fap drop. Today, we would have to pay $5-$10k for one, meaning those who started when they still dropped have a $10-20k advantage over those who didn't (the swing is doubled because they could either use it or sell it.)