I wouldn't say it's a waste of time. A friend of mine got into BTC a couple of years ago, and I thought it was ridiculous at the time - my perception of it was that it would end up obsolete and be absolutely full of scamtards... I was only half right.
I remember him getting a noisy little miner and shaking my head when he celebrated getting a couple of dollars a month, while his electricity bill was god-knows-what. Also, I found the entirety of it quite overwhelming, so I never pursued it.
Two years later, he reintroduced it to me, and I'm quite glad that he did. The possibilities with this are endless, and I am a bit miffed with myself that I didn't look into it when I was first introduced.
So I think for some, it just takes time, and small bits and pieces of information.
I haven't gotten anyone else into BTC, but it's probably because I need to put more effort into my sales pitch: "volatile digital space monnies you can use to gamble or buy drugs, hits, and child porn"... apparently not everyone shares my sense of humour.