The best way to entice new people into buying quality hifi products is to make them more affordable, to lower the cost of entry. That's probably why DIY is popular, because it allows people with midfi budgets to enjoy hifi quality.

I think hifi sales have been pretty consistent over the years, and I don't think the market is experiencing a downturn. I expect it is like other luxury items in that the very wealthy are unaffected by economic factors, but that most people will buy more when the economy is good and less when it is not so good or when people are insecure about the future. From my experience, it appears that high-end hifi is in a general upward trend right now.