I am not in this field - so people who are providing services will be more knowledgeable
Still:
1. Market is highly competive
2. without good Ressources and a value-add, you might not make much profit of it
3. proper marketing is key
4. There are many legal restrictions,
starting with proxies built on botnets
Following article is from the German Gouvernement:
link
Most people who start playing this field, are not aware of the consequences which come along with those proxies.
Yes, you can write as much as you want in the TOS (e.g: These are sneaker proxies- any violation against the ToS is not our fault).
We’ll, this might work in some countries - but mostlikely you are involved. Involved in a cyber crime, which is not predictable.
There are better income streams than this.
Take care
zotix