I saw this video featuring Eric Voorhees (founder of ShapeShift), talking about why we should be open to different cryptocurrencies. I thought he explained the psychology behind it so well.
Money is like religion to people. They become very emotionally attached to the cryptocurrencies they have a stake in, and will defend them fiercely.
They will often feel resentful when another project innovates and climbs the CMC charts. For instance when Ethereum nearly surpassed Bitcoin's markets cap.
Give that same person a little bit of another coin and watch their attitude change as its price fluctuates, especially to the upside.
I've noticed the same behavior among acquaintances who I've shared some crypto with. As soon as they own some, their attitude changes and they become more open, perhaps intrigued by it. I really think this is the best way to spread the overall adoption of crypto.
If you make even a small investment in other projects and start following their developments, your attitude towards them will likely change, and the industry will flourish more rapidly.