According to this (http://fashionmovie.tk/tv-dragon-calls-plumbing-a-job-for-life/) article, a leading businessman-turned-TV-star sees plumbing as a job for life.
That can have ‘downsides’ as well as benefits. Too many plumbers are probably still relying on the techniques, tools and skills they learned when they first started working. The world has moved on and there are now new ways of working. Plumbers have to keep up to date.
So, yes, it can be a job for life. But don’t think your learning stops when you get your first job. Like Drain Doctor, you need constantly to invest in the latest tools and technologies and in learning how to use them.