The bad news is that all gear (including your own) is full of bacteria. This is part of life and is best demonstrated by this: (1) Take a slice of bread out of a loaf and putting it into a zip lock and set it on a window sill. (2) Take another slice and drop it on the floor, pick it up, place it into a second zip lock and set it next to the first slice. (3) Watch the growth over the next few days.
The good news is that washing the gear will greatly reduce the bacteria so your natural protection will not lose a battle with it. It doesn’t matter that it is your bacteria or not... your body will lose all the same if you don’t reduce the dirt by washing.
The economics and becoming familiar with your gear on the other hand is where I draw my lines. Don’t forget the extra trip(s) required when renting gear compared to owning. I think most everyone goes to a dive shop at least once per day of diving (to refill their tanks). Since I have not bought my tanks, it takes me two round trips. My bride is still deciding on a suit so that’s two round trips plus getting different suits and those hassles. We know she needs to buy but buy what? Wet? Semi? Dry? We just haven’t found what makes her happy yet. When we do, my wallet has to be happy as well.
Best wishes, Greg, at putting a numerical value on all these factors so we can decide the best route. LOL