The only problem with your example is that Monero has a much bigger chance of becoming worthless than silver. I would be comfortable holding 100% silver, but much less comfortable being 100% in Monero. In fact I was 95%+ once in Monero, but I wouldn't recommend it to anyone
No, I'm not talking about 100% in Monero. I'm talking about the entire 5% of your cryptocurrency allocation in Monero. 100% of 5%. (1.0 * .05).
Let's just say your entire investment portfolio is $100,000. You decide that you want to put $5,000 in crypto. You have to decide what part of that should be XMR and what part of that should be BTC. If you think BTC is going to rise against XMR, maybe you will put the entire $5,000 in BTC.
In that scenario, you will be thinking about XMR's price in BTC, not in dollars. Because you want to know how to allocate the $5,000.