People started playing around with Bitcoin because it was something new and exciting, it was truly the first of it's kind! Ideas were being thrown around, more and more people started joining the ecosystem, mining was getting really competitive, Bitcoins found their place on Silk Road, etc.
The point I'm trying to make is that Bitcoin was first! And all that excitement and experimentation over time translated into monetary investments and architecture, something the alt coins will have to work really hard to obtain! Not saying it's impossible, just highly unlikely.
You have not actually answered the question. Experimentation and competitive mining do not translate to demand. Why did people ever start exchanging valuable things for Bitcoin?
I did answer your question, read it again. Do you think that the guy who sold a pizza for 10'000 put some sort of actual value on Bitcoins? No, it was all good fun. You can also include in the mix the idea that this technology seemed like it might go somewhere at the time (still does!) so it might not have been the value at the time that people were putting on Bitcoins, but the value in the future.
It's not that easy answering those kind of questions to be honest, without polling everyone who was involved in the community from the beginning and asking them what was their reasoning. So I can only speak for myself.
The point I'm trying to make is that Bitcoin was first! And all that excitement and experimentation over time translated into monetary investments and architecture, something the alt coins will have to work really hard to obtain! Not saying it's impossible, just highly unlikely.