I have an echo dot. All the Alexa skills I've got are free. You can pay a prime subscription to access more music and skills, but what is free is sufficient for me. I mostly play the radio on my echo dot, as we don't yet have digital radio and the reception in this house is diabolical. My grandchildren like The Magic Door, and Ditty. The magic door is an interactive storytelling skill and Ditty is a funny song maker. You'll understand if you invest.
On gogglebox a family were asking Google which is similar to Alexa, how to spell something, then they all started asking it silly questions, and having a laugh. I think it could be a good idea for older people, if you know how to use it - I understand that you can tell it all your appointments and it will remind you eg you could ask it "what am I doing today?" when you get up. A lonely person could probably talk a lot to it! Downside is that all the info is in there and anyone who knows how to, could playback everything, so it would be like someone looking in your diary etc. So depends if you have anything to hide and if you have family to stay who are likely to do that.