Re: Non-Golf Hobbies
I collect interstate road signs. I have some 250 of them or so. Only the blue numbered shields with the state names on them. There are about 10 of us across the country that avidly collect these things. Many of the signs are very difficult to find these days, if not impossible, because states are replacing them with signs with no state name on them and larger numerals to accommodate the aging population that can't read the numbers from a far enough distance. The original signs are "retired" which usually means going to a scrap yard for destruction. On occasion, I will buy other interesting signs. My favorite sign?

I have a real "CAUTION" sign from the San Onofre checkpoint. Yes, the one with the illegals running across the freeway. They removed these signs and destroyed them because of continuous outrage from the Mexican community. I was fortunate enough to have a connection that had a connection so I could get one. It is possible I have one of the only remaining signs, which makes it quite valuable.
All of my signs were obtained legally by me. I buy them from people who make a business out of collectible license plates, and who dabble in signs.
I also collect vintage arcade games. Right now, most are in storage, but I have the following original arcade machines: Berzerk, Burgertime, Crossbow, Domino Man, Donkey Kong, Donkey Kong Jr, Elevator Action, Food Fight, Galaga, Joust, Jr Pac Man, Jungle King, Mad Planets, Marble Madness, Popeye, Q Bert, Qix, Satan's Hollow, Super Punch Out, Time Pilot, Tutankham, and Wizard of Wor. I've had a Robotron and a Frogger, but sold them both recently. The Robotron was not a worthy piece for my collection.
These take up a ton of space. We will likely move back east where I'll be able to get a house with a full finished basement for a really cool man cave with games, a pool table, and maybe shuffleboard.
Finally, I'm into firearms. I don't collect firearms per se, but I have a bunch, and my hobby is more about serious training with the firearms, rather than just firing range pointing and shooting.