Do you buy gear new, used, both?

Mostly new, although some of it quite old now.

My last big purchase, a turntable was second hand, although I did buy some new bits for it.

I keep my equipment for years.  So depends on the type of component (amplifier, preamp, DAC, etc). Generally, I would buy used where there are no moving parts, age (less than x years), condition is an 8 or better vs price (discount from new if current model). For items with moving parts (CD players, turntables, etc.) generally no, but have done so on a CD transport and a phono cartridge where I knew the seller.

For open-box (new or returns) - condition, seller (store or individual) and discount from new selling price would be determining factors for me.

Almost everything I own is used. My new components are a roon nucleus and a Sonos Port

Except for cartridge and a pair of RCA cables I have nothing new in my system. And a few pairs of NOS vintage tubes.

Used gear, much of the time in the last dozen years. I took a break from two channel between 1989 and 2012. It was at that point my oldest son was heading to college and I felt that he needed a system for the dorm. That got me into buying used pieces to catch up with the pastime, mostly as a tourist learning about gear.

I was completely new to the idea of streamers on my return to audio. So the CXN V2, the CXN100, and the Bluesound Icon are all new. I've given two Bluesound Nodes as gifts.

My only new power amp is the CJ 62SE. An Aric Audio Unlimited II, which has been a test bed for 12AU7 tubes was new at the time of purchase. The turntables were both new. The Omega Super 8 HO monitors were new.

The rest of the gear across each system is used. Some of that equipment was sent to the factory for full servicing. I see that as the occasional cost of doing business.

I'm going to go to AXPONA to get a perspective on what's possible in the world of new gear, but I do like scanning the lists for interesting stuff that's for sale as used items.