Bitcoin is not even close to a sure thing in comparison to metals so it's very hard to recommend a higher BTC allocation than gold or silver. You have issues to deal with like the rough consensus attack and the legal system outlawing it and thus crippling it's usage and market cap.
Then the fact that you need around 50 TPS (8 MB blocks) + Schnorr signatures for BTC to be a viable global currency, and then I think the current estimate is going from 1 MB blocks to 8 MB blocks just to quantum computing proof the chain, thus making Bitcoin require HUGE blocks with the base 8 MB block size + the additional Shors/Grover's algorithm protection overhead on top of that. Or it could stay at 1 MB blocks and turn into something like the SWIFT network, who knows.
I'm not really sold on the Lightning Network, but it might have some use to alleviate some of these throughput issues. And maybe the quantum computing brute force attacks might not be an issue, but maybe they will. Too many variables still up in the air to pretend that Bitcoin is equal to metals if you're betting your savings on it and wish to avoid fiat dollars.
Bitcoin is still a speculative gamble at this point while I consider throughout all of history, paper currency is a derivative of metals and not vice versa. No matter what Bitcoin does, metals will always be at the base of Exter's pyramid with Bitcoin above them. This means I don't think it's really possible for Bitcoin to beat metals in market cap, and if Bitcoin did, you would be living in an irrational market which would then collapse.
I don't consider metals a gamble or an investment. I consider paper currency a receipt for metals just like they've always been.