Why are there so many new online marketplaces popping up?

One reason is because there are more tools available to create online marketplaces.

For single-sided marketplaces, people can use Shopify, BigCommerce or WordPress (with plugins).

For two-sided marketplaces, people can use Sharetribe, WordPress (with plugins) or hire developers to create their marketplace.

Other factors include:

• The costs are getting lower
• Shows like Shark Tank & The Profit are making it seem easier
• People are now more used to having hundreds or thousands of followers. I feel this leads to the perception that they could attract this same amount of people to use their product.