I’ve got two bolted trees under my belt… I put a very slight up angle to the hole for peace of mind, and make sure I’m applying fairly perpendicular pressure when I step. For example, I don’t swing far to either side in a way that would put outward pressure on the opposite bolt. I also bolt wide enough that if I took a fall I’m less likely to meet a bolt, with say my upper leg or abdomen. Three climbs in the bolts feel totally solid and none have moved at all. Also, they’re pretty tight in the holes and I imagine your weight creates some thread engagement / bite in there.