Is it possible to mining BTCitcoin without any capital/asset?
If you can "borrow" your mate's computer to mine altcoin and then trade it into bitcoin, then yes, it's possible.

Day's of mining with CPU and GPU are really over. In most cases it cost's more in electricity.
You really need to look into asics. But it will take cash, you can't do it with no assets. You could also buy direct but again takes money
aren't the mining days over for most of the people at home. even if you buy asics then the question will be : how long will it take before i break even, if ever.
Well that depends on a lot of factors.. Price for electricity, using the miners for heating if you live in a cold climate. If you are a believer in that the BTC price will increase in the future.
for example here in europe it is impossible to do home mining as prices of everything are way too high. investing directly in btc seems a better option.
Lets just say that mining without proper equipment and hardware is impossible. Mining anything without investing money is unreal. And even if you have some spare cash to invest it is probably waste of time and money as we are the time and age of full specialized mining farms rather that individual miners so unless you have like $100k to spend for hardware and setup mining is out of the question.
wouldn't it be a better option to invest or buy yourself a certain percentage of an established pool rather than buying hardware with $100k i think it will make you roi considerably faster.
I don't think were talking about setting up a pool. More like a data center. And depending on price yes chances are better off to go to a existing data center with your equipment when talking about 100k.
To go big scale is not cheap if done right. You could do it on the cheap side I have seen it done, but your better off going to a established data center. With a much smaller number you could mine at home if cheap electricity, but 100 k worth of miners is a heck of a lot.