There is no fixed answer to the question, and it depends on the individual.
Yes it is an expensive hobby if you want high standards and are driven by technology. There is nothing very wrong with this. We are humans after all.
Although some argue than digital is cheaper than films, I can present another perspective to show it is not. It may be cheaper if you are talking about price per image. You can shoot like crazy with digital and erase images at will. In the past, with films, every time you press that shutter, it's money. So in that sense digital is cheaper.
But if you think hard enough, you will realize many of us are changing cameras often, be it DSLR or digital compacts. You can't help it. Digital technology is not quite settled now. If you have a digital cam that was made say 5 years or older, you will know how slow the auto focus can be, how noisy images are even at ISO400-800, and the LCD screens are super small. It is this constant chase after better cams that will eventually make this hobby expensive. Even more expensive than using films I suspect.
Also with film cameras, you can get a mid ranged semi-pro SLR packed with many advanced features for about S$1300. Today, that same cam in digital equivalent costs at least S$3500 or more. Strangely, maybe we have become more affluent or are more willing to spend in the digital age for us to dare splurge a few grand on just a cam body. In the past, this would have been unthinkable. And the depreciation of digital cams is way too fast. Your "solid" $3500 cam today will probably worth much less than $2000 in a mere 3-5 years' time.
Another problem with digital is that, you can't help upgrading because like I said above, the technology is still developing. The heart of the digital cam lies in the sensor used and cam manufacturers are constantly improving them. Sorry for those who argue their old equipment can take better pics than the newer cams. I disagree with that. Photographer skills being equivalent, newer digital cams can produce better images because they have the edge over older cams in producing better tones, less noise, etc.
Amazingly, even before newer models are released, people are already enjoying the process of speculating in the forums what is to come and of course, planning which cam to buy once it is released. How can it not be an expensive hobby if this is what you do?
With films, quality of your images is in the films you use. So you can use a 1970 cam or a 1990 cam, assuming your lenses are in good condition, the 1970 cam can produce equivalently nice pics than the 1990 one.
The only way digital photography need not be too expensive if we can curb our desire to constantly upgrade. That is, if you can stand not keeping up with the latest technology. Think about why people change computers or mobile phones every few months or years and you get the picture. It's difficult not to change, but can be done. If that is the case, photography is affordable. My solution is to stay away from the banal talks in photography forums (CS forum included) about buying this and that as far as possible and simply enjoy the process of taking pics.
