Even if bitcoin's investment thesis is stronger today than it was 10-15 years ago, bitcoin still is not guaranteed to be profitable in the future, and every person still has to figure out his own level of balance in order to not reck himself in terms of overly investing into BTC, even if he might end up being correct about bitcoin price direction projection as being up.
This piece literally sums up the whole idea of investing wisely which is by investing an amount of money you can afford to lose. Investing with a sense of moderation. We need not put all eggs in one basket and by way of this in figuring out our respective level of balance to avoid reckage is by diversifying our investment to other physical assets within our reach that we know can be profitable in the long run. Now this doesn't mean that bitcoin doesn't have a bright future ahead to do better but it's just a way to guard oneself against future uncertainties everything being equal.
Confidence is in yourself, if you have made up your mind to buy Bitcoin why should you diversify your assets.
In my opinion, if you want to be successful, just get past your doubts, it is true that investing is not with all the money we have but only a part of it, aka we invest with the DCA strategy.
Saylor alone who bought thousands of BTC did not diversify his assets, not to measure it but he knew BTC would not die or lose value if the internet still existed in this world.
Also, you are still hesitant about bitcoin because your post has various meanings that can be explained because you said you have to diversify. It is not wrong, but try to stand with your beliefs.