The vision of the BTC community is that on-chain scalability for payment has no chance anyway (1MByte is capable of 5 orders of magniutde less tx/sec than VISA), so using second layer methods (like lighting network) to do payment is absolutely inevitable anyway. So they keep blocksize small enough that a regular guy with a regular PC can realistically sync-up the network and become a full node, because they think this is needed to be truly decentralized and secure. This possible lighting network future, and also that BTC is the most battle tested, and most forked coin, and has by far the biggest network effect are all included in its price.

My portfolio contains other coins from the top ten so I hedge it with other solutions for scaling, but BTC's share in my portfolio is close to its share in the crypto market cap (a bit less, admittedly).