Dispute / request do I just refund money for lost items?

Hi, I just listed a few PS4 games this month. A power seller (28,000+) bought a (like new) ps4 game from me for $44, something he sells for new which I found very strange for him to buy this second hand item when he sells new ones.

I thought maybe he didn’t want the competition in that listing or something. Anyways I ship it to him and 10 days later he starts a dispute claiming it’s not delivered.

I told him to wait another day or two it should arrive as I’ve sent out 300+ items over the years, never once had a lost item.

But I get the vibe he just got the item and knows without tracking it’s a free $44 to him if he claims a dispute.

I know the rules and EBAY sides with the buyer and I have no tracking so I’m screwed. I guess in the future I’ll add tracking on items over $40.

Never had a dispute before, so in 4 days he can get EBAY to refund his money and that very negatively affects my account? Should I just refund him the money and write it off to experience?

Thanks