There’s the famous observation that the value of a network grows as a function of the square of the number of nodes, and also many of these services/products double their userbase every N months, with N decreasing as the service gets more valuable. So the value/importance of the service grows hyperexponentially. I’ve never met anyone in my life that has a good intuition for hyperexponential growth—most of us even struggle to comprehend exponential growth.
As an aside, pay no attention to market predictions—some of the worst predictions in the history of business (a market for 5 computers, a market for 900,000 cell phones) have been the most costly.
If some users really love what you’re building, engage with the service or product as an important part of their daily lives, and interesting new behaviors keep emerging as you grow, keep working on it.
There are two time-tested strategies to change the world with technology. One is to build something that some people love but most people think is a toy; the other is to be hyperambitious and start an electric car company or a rocket company. Most of the “intermediate” companies, although it would take a separate long post to explain why, end up not having a big impact.
One, don’t claim you’re changing the world until you’ve changed it. Two, ignore the haters and work on whatever you find interesting. The internet commenters and journalists that say you’re working on something that doesn’t matter are probably not building anything at all themselves.