Most people that use Max in their work are either involved in the arts or academia. I had a similar question during my undergraduate degree - "Will someone pay me to make patches?!". Yes, they will, but it's more than likely that you will need plenty of other skills to go along with it (familiarity with hardware and programming languages which).
I've done sound-design for video games, exhibit/installation setups, and music software.
"And how did you get to do that?"
If you're lucky, you might find a job or two posted on these forums and elsewhere online, but most of the time, you connect with people in a particular field, let them get to know what you can do(by sharing patches or performing with them), and then when they have a project that can involve max patching, they'll think of you simply because you put yourself out there. Not many businesses are proactively looking for Max/MSP patching(especially during a recession), but if you put yourself out there, you increase the probability that someone will think of you or your work when it's needed. (also, use common sense to focus the probability more: you have more chance to find this work in a large city; you have more chance to find this work, steadily in or around academia, not so steadily in or around other struggling artists(though you might learn more from working with each other); you have more chance of finding this work if you are not desperate to make a living solely by this, etc.)
I make apps for museums and exhibitions, multiprojector with blending and geometric corrections, games with wii controllers, multitouch surfaces, show control and more, and I get paid! Good for me haha...
@Gerardo : a bit OT but reminds me of a story about Ornette Coleman recording the score for 'The naked lunch' with a symphonic orchestra (London's if my memory's right). After a take, one of the orchestra musician comes to Ornette and asks : 'I can't see your score, what are you playing ?' So Ornette explained he was improvising along the orchestra score, inventing melodies and textures on the fly. And got answered : 'Oooh really ? And you get paid for that ?'
I'm currently studying sound design in Denmark and I'm trying to figure out what my opportunities are.
I've done alot of Max/MSP projects during the last year or so, but my education is primarily focused on producing good sound.
And although i love good music and good sound, it has occurred to me that i shouldn't be working with sound as a producer, studio-engineer or traditional songwriter in the digital realm. I easily get tired of those situations.
Making patches for correct playback of small pieces of sound, connecting to X-Box controllers etc. is more up my alley!