It really depends on the market size. If you have 1M users which are 40% of the market, it's often difficult. (and expanding in a larger market often implies risks similar to a regular startup).

But if you are in a 1 billion market, your growth rate is impressive and you make data-driven decisions to manage your future growth, then yes, 0 to 1M was harder.

Warren Buffett has a quote for this: "Life is like a snowball. The important thing is finding wet snow and a really long hill". Even if you find wet snow, it's important to look how long the hill really is.

Larry Page uses the toothbrush test: he wants to invest in products that people would use like a toothbrush, twice each day.