For me it's just another asset, no need to use it to pay for things

Speculation. Service provision, infrastructure provision (hosted nodes).

It's not very good for payments (that are small and/or frequent -- and no Lightning is bad too (state channels are capital-inefficient)) despite what zealots would have you believe and it's not very well decentralised on a geopolitical level either.

Bitcoin is a good introductory MVP example of what a blockchain is and it's greatest contribution is Nakamoto Consensus.

i live in venezuela and i buy and sell bitcoin every week because it's the easiest way for me to get the local currency on localbitcoins so i can buy groceries and such. i only use it for this purpose

i've also sent money to people in other countries using localbitcoins. it's really helpful for me in that way. they just deposit money into people's accounts and it's worked flawlessly for me so far

Is there any tax liability there?

to be honest, i don't know. they're always changing what's allowed regarding foreign currencies and i don't know what the law says right now

Mainly as financial speculation. I'm genuinely curious about the answers to this question

I use it to buy all kind of things on the internet.

I also use it to store a small fraction of my net worth in a place that is out of reach of anyone (ex-spouse, current spouse, lawsuits, governments, etc...).