I guess I don't really understand the idea that lenses like the new 200-400L are for professionals only. I think it all comes down to available resources, esp. for hobbyists. I know my own purchases for hobbies fluctuate depending on how well we are doing at the time. I'd be willing to bet that quite a few of these lenses will find their way into the hands of amateur enthusiasts as well as professionals.
As has been stated in various POTN threads over and over, some hobbies are far more expensive than photography. I have friends who own $100k sailboats but only get out on them a few times a year. For that pleasure, they spend thousands on maintenance and marina fees each year as well. Same with hi end audio equipment.
If someone has the cash, I think it's cool they use some of it for their interests away from work or to enhance their retirement years.