As with so many things in life, it doesn't work like that.
The price of Bitcoin is largely driven by speculative trading and fluctuates wildly accordingly.
It's best avoided for this reason alone.
...Ethereum is the next most valuable by a big margin and there are many applications based on it's blockchain workings, so it's likely to be much more practical to use as an alternative currency in the longer term, not least because the max supply limit of Bitcoins will make them impractical over the longer term.
And maybe it's a good thing that the current market valuations of BTC and ETH are so different.
I wouldn't consider opening a position in BTC at these prices, and even if I did, it would be purely speculative.
ETH on the other hand is something I am interested in opening a small position in.
It's far less volatile than BTC, and seems to be more useful.
It's already leaps and bounds ahead of the competition, and ETH 2.0 is due in... 1-2 years??
If digital currency is the future, then it's most likely going to be a Central Bank issued one - not the adoption of Bitcoin, or Ethereum.
So when we remove that from the equation, we are left with the blockchain technology itself, and this is where it seems ETH has BTC beaten, hands down.
You touched on an interesting point however, and that's the max supply limit.
From what I can make out, the max Bitcoin limit of 21million will not be reached until around 2140.
Though apparently the source code could be changed to allow more...
Ethereum has passed 100milion, and apparently Vitalik Butterin has proposed a cap at 120million (or 144million if 120 is passed by the time it's agreed). So if it has no cap currently, and they can put a cap on it... then I assume a cap can be removed again?? Meaning that technically, neither is finite.
From what I have been reading, ETH is about to go beast mode in the coming months (year?) with ETH 2.0
This will make ETH far more efficient than it currently is right now.
Ethereum 2.0 is coming – Here’s what you NEED to know