In my opinion blockchains are valuable because they offer an alternative. Bitcoin itself was born after/during global financial crisis of 2008 as an alternative to modern financial systems. Once there is an alternative then it is up to the people to choose if they want to give any value to the alternative, in this case bitcoin and blockchains in general.

Every human interaction, every choice in essence creates or at the very least assigns value. Most common choice is how to spend time: create something, go to work, watch tv, hang out with friends, spend time with family, engage in sports, travel, spend time on social media, learn new things, various hobbies, etc. One way or the other we try to give different value to different things at various times. I think it is all about options available and choices made.

For example, here on Steem value is not just created by posting blogs and exchanging upvotes, I think real values comes with people choosing to spend their valuable times in various communities, networking, building new things. Everything done on Steem can be done elsewhere, but Steem is providing alternative. Is it a better alternative that can go mainstream? Depends who you ask. Nobody knows. It will be determined by choices people make.

Blockchains have a great potential to empower ordinary people, yet these potentials aren't without risks. Best technologies are always the ones that are easy to utilize. I think, making them simple to understand and easy to use is where blockchains might be failing at the moment.