Well, I was at one point a collector of amiibos. I have a very near complete collection of the smash amiibos, the only ones I'm missing being the mii characters (I hate them and refuse to buy them), Lucas, Roy, Ryu, and of course Bayonetta, Cloud, and Corrin since they haven't even been released yet (at least I don't think they have been? I haven't really kept up with the releases nowadays). Before I got my first amiibos from my now ex-girlfriend, I didn't think they were anything worth buying. They just looked like overpriced figurines that I would never even use if I got them. Sure there were a couple that I wanted because I mained those characters and I would've loved to have a little figure of them to represent my love for them, but I didn't think I would ever bother getting them, being that they were 13 dollars+ a pop..
However once I got my first ones, which were Samus, Peach, and Yoshi, I was basically screwed. I fell in love with them, not immediately but over time, and I began looking up amiibos that I didn't have yet but would probably enjoy having. It was a slow build up from just the characters that I liked into rare figures that I would just so happen to run into when they were back in stock in store. When I saw the rare ones that people were selling for like 30-40 dollars, I just couldn't pass up the opportunity to have them while they were market price because I felt like I would never have the chance to get them again without spending a fortune on them. So after I started getting characters that were rare even if I didn't much care for them, I started getting really into it. I would ALWAYS have tabs open with amiibo trackers that would play loud obnoxious sounds whenever they were back in stock. I would look at amiibos every time I was on my computer. I would keep up with all the latest releases. For certain amiibos that I REALLY wanted, I would even go to the stores the day before they released and wait outside in the lines just so I could assure myself one of them (yeah, it's dumb in hindsight). I now have a whopping total of 78 amiibos in my entire collection (including AC, Wooly World, Mario, Shovel Knight amiibos) and a very attractive looking wall lined with my collection of Smash amiibos.
If you add that all up, that's over $1000 dollars worth of amiibos ._. .. I never really spent over market price for any amiibos except for maybe one or two (only one I can think of at the moment is King Dedede which I payed about 25 for because I thought I would never get him at a cheaper price and he is one my mains). That is an absolute ridiculous amount of money, and I honestly want to sell them. I've been trying to sell my (near) complete collection of smash amiibos since that amount of money would be nice right about now, but I don't think anyone will be willing to spend an upwards of 700 dollars on a collection of amiibos right now (and that's breaking even, not making a profit). In hindsight I almost wish I didn't get into the amiibo craze, but I also don't really regret it because I absolutely love my collection. It's super nice to look at and I'd really rather not sell it, but money is tight right now.
But yes, all in all, I completely agree; it's a money grubbing scheme. For me though, even now, it's sometimes a very hard one to resist because of how appealing the character models are and just how much I love the characters of Nintendo. Luckily I've been able to resist buying them and the last one I bought was my Shovel Knight amiibo (and almost definitely the last one I will ever buy unless they come out with something I just simply cannot resist like a Shantae amiibo or something)