I have a ton of hobbies and limited time. Over my life I've been into the following: - coin collecting - Medieval and Russian/Soviet coins. This is expensive and it isn't all that time consuming. After you have looked a a coin and placed it in display, the only fun comes from showing it to others that have not seen it yet. I stopped doing this years ago but if I were a millionaire, I'd definitely get some expensive Medieval or Roman gold pieces. - guitar - I have played for a long time (15 years) and it is really fun. But, for it to be fun you have to put a lot of time into it. A great setup (good quality guitar, good quality tube amp) can cost easily $1,500. It also requires almost daily practice just to maintain and significantly more to get better. - Archery. Cool in theory. In practice I ended up with tons of red welts on my arm and lived in fear of the bow breaking. Sold after 3 months and got out. - Drones - first I started with indoor first person view (FPV) drones. Then I got a Phantom 4 and then a stunt/racing drone. Stunt/racing drones are where the fun is at! To get into this, expect to spend about $300 for a transmitter (everyone calls it the controller..) that can be used on many different types of drones. Spend another $60-200 on FPV googles (I spent $60 for a cheap setup). Minimum $300 for a decent drone with carbon fiber and durable construction. Conventional wisdom says "practice on cheaper drones" first but this is actually more expensive. The cheaper drones are harder to fly and have a lot less power. A strong gust of wind and there it goes, while my Blade Conspiracy pretty much can go or do whatever I want it to with ease. I can do quadruple back/forward flips and have a camera footage to prove it! If you are good the parts will fail before you crash it (as mine is currently awaiting a new engine). - aquariums - This is my favorite in terms of expense vs "what you get out of it." When we moved to our current location I got a 69 Gallon Red Sea E Max that is awesome. I want more when I can afford it. A few grand on a saltwater tank is a high fixed cost but if you depreciate it over the life of the tank it isn't as much. I have several other smaller tanks (two fresh, one other 20G saltwater) and this hobby has the best Variable Cost per Fun ratio. - video games. I was once somewhat into first person shooters. I played Counterstrike on the internet a lot in college (this was in 2001) and was once top 5% in the world in Battlefield 2. Was it worth it? Nah. It has low variable cost, but in terms of stress relief it didn't beat aquariums. In terms of excitement, drones are tons more fun and feel more real. Single player games all have a trick to them as well - I have played so many single player games on the hardest difficulty level and see that the AI cheats and there is often an exploit to win. It gets boring.