What's wrong with collecting? I think it's awesome, especially for vintage / rare instruments. If you're not broke and you have the space for it (like trumpets take up so much space to begin with) I see nothing wrong with it.
I sort of used to collect trumpets / cornets. I would buy them, play them for a few weeks and then sell them on ebay, sometimes at a loss, sometimes for a profit. Now I'm in my "professional" life and I don't have time for those kinds of things, but I got my hands on a lot of older horns and could tell you which ones I liked and which I didn't like.
Here are my favorite "old" brands:
Selmer Paris Vintage 1960s-70s --- Probably the most underrated trumpets out there. Just think Maurice Andre
Olds Ambassador / Recording / Super Recording --- Very good for a commercial type of sound
Martin Committee --- These are still the G.O.A.T. of jazz if you ask me. The slotting is almost non-existent. Slippery as a snake.
Lefevre / Various French Cornets --- These are small-bore cornets from the turn of the 20th century. Not useful in a modern band setting, but they were really a piece of art as much as an instrument.
Anything ever made by Getzen --- These are some of the best value instruments ever made. I have no complaints about them.
Vintage Conn --- Mixed. Some of them play well, others are total dogs. They tend to be built very solidly.
Old Soviet Trumpets --- Helps you learn to appreciate capitalism.
These days, if I have a musical moment, it's usually with the French Horn. Something about the lower pitch and the rotary valves draws me in. I purchased a french horn by the manufacturer Jiracek. They are a Czech company just down the road from where my father was born. Kind of a neat thing to remind me of my heritage, and it happens to play well.