I won't say that you can't make a career out of scootering, but it's very unlikely. Even the most of the top pros don't make that much money. Ryan Williams has been pretty successful witth the Nitro Circus, but I have no idea what he makes. As with any extreme sport, your body (age, health, capability) determine your earning potential. Because of that, you're not going to have a very long career, so you should always have a more stable backup plan. Pursue scootering, but also get an education so you can be valuable within the industry beyond your riding abilities. That is, you could get a degree in marketing and then work for a scooter manufacturer's marketing department. Or, get a degree in mechanical engineering and maybe you could design products for them.