What other hobby...

has has an infinite number of variables like this one?
Audiogoning. 😊
Auto detailing.  Guys will spend thousands on 1 tub of wax. An infinite number of detailing products on the market and the enthusiasts are just as vocal about what is snake oil and what isn't. 

Right. They all do. Any time anything seems simple, look around, you're missing something.
HO Model Railroading
Wood working

AND the greatest hobby of them all;

Retirement, is the greatest, sport, hobby, and THING ever invented.
Too bad it took me over 45 years, to figure it out..

Favorite animal.... Terriers, and Hummingbirds, Both just like me. ;-)

"I'm a squirrel watcher
I'm a squirrel watcher
Watchin' squirrels go by
My, my, my

I'm a squirrel watcher
I'm a squirrel watcher
Here comes one now
Mmmm, mmm, mmm

I was just a boy
When I threw away my toys
I found a new pastime
To dwell on

Whenever I detect
Members of the other species
I play the game I do so well, oh

I'm a squirrel watcher
I'm a squirrel watcher
Watchin' squirrels go by
My, my, my

I'm a squirrel watcher
I'm a squirrel watcher
Here comes one now"


Chess and audio and chess used to constantly battle it out for my attention.

In the end audio won out for fun value but I still enjoy watching it on YouTube.

Especially all that trash talking on Coffee Chess.

I'm into movies. To infinity, and beyond!
Photography.  At least we got past the analog vs. digital debate (for the most part).
Even though color is the mainstream preference, monochrome may be making a comeback...
Remind you of anything in audio?
Mono/Single speaker audio system?
God is in the details
Other cool stuff such as vintage Rolexes.
Every hobby in the world
Owning Harleys. There are infinite ways to customize a bike, lots of time tinkering, and time and money on repairs. 
Walking under the sky, and reading a book, listening music, i dont need hobbys, except communicating with mimosa plants...

And dont laugh, it was already proven in 1925 by Jagadis Chandra Bose that plants react and think...He was voted in the 7 most important people in Bengal history and i read his book when i was 25 years old, 45 years ago...

It is NOT the same Bose that in physics is the creator with Einstein, of boson condensate and statistic concept, Satyendra Nath Bose ....2 genius in physics tough, but my Bose is also a genius in physiology....


Porn ... ;-)
Without love boring like audio on headphones....
Is that a hobby or a sport? maybe both..  ;-)

I forgot about playing with the cameras, Love my old Minolta and newer Sonys. Just love fiddling with them..

Infinite? That's a pretty big concept. What hobbies have "infinite" variables? None, and imo not even close. I believe we are on the very, very low side of "infinite" variables (unless one wishes to play fantasy games intellectually). Of course, I do believe the OP was using the term loosely, not technically.  

When you begin to gain appreciation of the vast spectrum of performance, even when aggressively experiencing a wide variety of systems, it's a humbling experience. You realize that though the variables are not infinite, they may as well be when it comes to the various outcomes in systems and their performance. I build dozens of systems a year, and the spectrum of performance does not narrow, it widens. 

But, and this is critical to me, the enjoyment of variety is endlessly fascinating and rewarding. I spent an hour last night discussing with a manufacturer one Dip Switch inside a DAC that alters the entire performance of the DAC in several ways. It's another whole "infinite" field of variables inside the machines, as our DIY and manufacturer sector knows!  

Ceramics is pretty close to infinite. Humans have been making pottery for 50,000+ years and have barely scratched the surface. We have only begun to understand what happens inside the kiln in the past decades. The atmospherics are mind bending. And that is but one small arena within ceramics. Glazes, clay-body glaze interface, clay bodies, forming and shaping. On an on. 
@twoleftears We have a saying at our local camera Meetup Group (which is inactive now) - If it's Black and White, it's art!
I started to say, "sex", but- with all the new, designer diseases out there, it’s now more of a spectator sport.       SO, yeah- porn and Harleys, +1 each.       Then again; I have known people that made collecting diseases SEEM like their hobby!       Kinda went with the Harleys.
Cooking and
Fountain pens (you know, the things some folks call "ink pens" )
I think I'm gonna start selling sildenafil on this web site. 
Collecting music (CD/DVD/Vinyl).
I also got a kick out of dekay's answer. Although, squirrels was code for "chippies.
"Even though color is the mainstream preference, monochrome may be making a comeback...
Remind you of anything in audio?"
Vinyl, of course.
"I collect foreign tennis balls and knit humorous cummerbunds"
George Carlin
Squirrel hunting......much better in dumplings than chicken.

Wine? You don’t say. Well, me too - North Rhone, Burgundy.

Also DIY audio.
+1 for wine in all it’s variations.

Homebrewing.  The variables and choices are endless.
Collecting vinyl albums! Especially when you get them at 45rpm.  You need an album for each side of a regular Album.


Organizing garage