Yes there are exceptions to every norm but the norm for these types of apps are cheaters, drug dealers, and pedophiles.
except that for VPN's, cheaters, drug dealers, and pedophiles is NOT the norm. they are the exception.
even among the dark web, which i also go on all the time, most users are just curious people who want to remain anonymous. the drug dealers and pedophiles use bitcoin wallets, often multiple bitcoin wallets, to transfer funds anonymously. there are less than 30 million bitcoin wallets with enough bitcoin to maintain a wallet in them, and they are most popular in countries with the most capital controls. block chaining and cryptocurrencies are more broadly understood today than they were several years ago, and it is much easier to trace those transactions than anyone originally thought, but that doesnt stop the non drug related transactions. its current value is a testament its popularity for avoiding processing fees and capital controls, so the greater risk of getting caught dealing drugs did next to nothing to stop its popularity.
and then there is the TOR browser. with about a 100,000 downloads every day, there simply aren't enough bitcoin wallets to claim that a majority of people who use TOR are dealing drugs or doing something illegal, considering that most of the dark web markets trade in bitcoin. more people download TOR every year than all of the bitcoin wallets that have ever existed. most people just download the browser to use it like a VPN, or because they are curious about onion sites.
so yea, drug dealing and child porn is NOT the norm. VPN's and TOR may be the primary tools used by drug dealers and pedophiles, but most people who use them are not drug dealers or pedophiles. and as for cheating, neither VPN's nor onion browsers really help much with that.
the most likely answer is that someone downloading them is simply trying to bypass blocks and censorship, and to maintain anonymity.