The world of technology is evolving every year what if in future a new tech is been born that can kill crypto or works better than crypto won't this kill cryptocurrencies?
There will always be innovation in new technology and when that happens we might see better methods than cryptocurrencies in covering the topic of decentralized financing. However that cannot stop another system from being used. Essentially a system does not die out unless the people using it stop doing so. I dont think bitcoin will end up in a reason to be stopped so it is a safer bet. But altcoins do die out when their use stops and because majority of altcoins have no use case, the end result becomes similar.
Also I heard that super computers can get through all crypto wallet keys easily in a matter of days, true or false?
The quantum computing argument has been debated and the essential gist of this is that it will take a long time to actually develop and if it does, why would the creators attempt to use it for a malevolent purpose of stealing someone else's money? But the real thing is that it is a long way in future and by that time bitcoin will have already reached a much more important status.