It has nothing to do with the intent of “personal gain” or what it’s for. It’s entirely about whether it is earned through trade or taken through fraud or coercion.

To personally gain, entirely for your own benefit, by doing a service for other like mowing their lawn, fixing their plumbing, or whatever. This is the very definition of helping others to help yourself. Thats what trade IS

There is trade, then there is theft. If you are voluntarily trading, there’s nothing at all wrong with personal gain. To the contrary, it’s what makes the entire economy work and why money is a tool to force people to cooperate, even those who would rather not.