>I don't know why you were voted down. Had I invested heavily in learning Silverlight a couple of years ago, I would find myself with my thumb squarely secured up my own ass.
Not really, as someone who specialised in WPF since it's latter beta stages, I still am finding plenty of work at a very good rate. Same thing goes with silverlight, even in a discontinued state, it still is going to have years and years of bug fixes. Just no new functionality.
The fact is, even today with all the frustrations I have with WPF been 'unfinished' it is still a lot more pleasurable than HTML/Knockout or something that tries to make HTML palatable.
A quick search in London on your favourite job site shows that learning WPF hasn't been a waste of time, my skills are not in a vacuum, I also have strong OOP skills, whilst knowing how to run software projects. Plus learning something is never bad. Obviously I wouldn't recommend someone learning it now. But compare it with whichever flavour of the month framework people are loving right now, people who've learn say Ruby on Rails aren't as fashionable as say Node.js is right now. But just do a quick jobs search in London and you'll see that you'd be better off on average doing WPF/Silverlight than RoR.