At some point the discussion became less about paying to learn and more about even trying it out at all, which is what bothered me.
I was including SDN as pure entertainment.
Personally, I could not give a crap less what "the circles I am trying to break into" think about my 'me' activities. If they don't like them, I won't tell them - I usually avoid telling them I ride motorcycles, for example, I ABSOLUTELY hide my SDN involvement from everyone on the planet, ever, I don't advertise the fact that I bought a few sutures and an anatomy coloring book which I enjoy for fun (I like coloring, why not color this, if it's just as enjoyable?). That doesn't mean I shouldn't do them.
OP wants to try something out that they may enjoy and which doesn't hurt anyone. Now, they'd be silly to pay for it, or to put it on an app, but other than that I see no issue. I see HUGE issues with people telling them that that's not an ideal leisure activity, they should try something 'better'.