Why would anybody trust criminals to pay them over time?

Because if they don't other people will hear they don't pay and won't sell them 0days

How long do you figure a criminal reputation typically needs/wants to last? I have always been skeptical of “black market credit ratings”. If you happen to build one up, it’s likely only in order to rip someone off at a higher price and cash in the value of it. It’s not like you’ll need that good rep for your retirement.

	▲	applfanboysbgon a day ago \| parent [-]
		ShinyHunters has been "in business" since 2019 and it is their reputation that resulted in eg. Canvas paying their ransom this year. Without that reputation, it is unlikely a large-scale ransom would have been paid, because the reputation is what gives them credibility that paying the ransom will actually result in the promise being upheld.