Not to worry... DIY'ers won't take away your livelihood.
For every one person that comes here asking for advice, there are probably a thousand others who pick-up the phone book and call a plumber. They just can't be bothered. They're too busy, and don't have the time or inclination to deal with plumbing of all things. Besides most folks would rather pay someone and enjoy their weekends.
And pay they do... here in NYC plumbers bill $200/hour with little complaints. In fact, it's probably among the highest paid "trades" to be in. They're certainly making more than electricians, carpenters, drywallers, framers, roofers, tile workers... a lot more.
Many who come here asking for advice are serious about doing the job right, and should be applauded for that. Would you rather they don't ask and screw things up?
Nobody posting here is taking any bread off your table.