Moral aside of shooting mates' wedding and charging for it(!), but as soon as you use equipment to earn it's a business/side gig. You may not like it but I'm sure tax authorities of any sane country will disagree with you.

For the rest I actually agree with you and think credit system is predatory and that if one can, one should take advantage of it. Just that buying something on credit because want, and using that something to earn money are two fundamentally different cases.