Bitcoin has 2 weaknesses.
1. The bitcoin encryption could be broken. Be it QC or a clever algorithm or whatever. That would make bitcoin almost worthless overnight.
2. The blockchain grows every day. Unless something is done, eventually it will become too big. And then one by one the nodes will quit supporting the network.
1. Technically true, without a doubt. But let's take note that Bitcoin's encryption being broken is going to be the least of our problems if the encryption was actually broken.
That is not comforting at all. I have heard the same comment before, but it is not less of a problem, if others (eg. banks) are having problems too. If you compare to gold, banks having problems is not a problem with you holding gold.
Compared to gold, bitcoin is unsecure. Gold can't lose all of its value overnight.
Not sure how you even compare Bitcoin's security to a piece of metal to be honest. Also, remember that gold can a lot more easily be faked. To be completely sure if the gold you're receiving is actually legit, you'd have to do some chemistry or some applying of pressure or go ask some business to verify it for you.
Bitcoin can't be faked, and it is one of bitcoins strengths. But if you have gold that has been verified to be real what could happen to it besides it being robbed? Nothing.