I made my money by creating software and engaging in voluntary transactions with people (mostly wealthy people) who wanted to transact with me and would've been worse off having not done so. It was totally positive sum with no harmed third party. A very large proportion of transactions (plastic surgery, sports cars, entertainment, holidays, restaurants, personal trainer, Netflix, etc) are of this nature where the rebuttal that "it's not really voluntary" doesn't apply in the least.