The business of appointment scheduling software. Calendesk 100k in arr?

Yesterday, I was reading a post from the founder of Calendesk that they are making 100k in arr. I was surprised because I thought that the market was small. I ask myself how big is the market.
it turns out Appointment Scheduling Software Market was valued at USD 223.83 Million in 2019 and is projected to reach USD 588.10 Million by 2027 according to verified market research.

so that means if you are in this market, the fastest way to grow is to find a niche within the market segment. for example, after a quick Google search, it turns out that appointment scheduling software is widely used by real estate companies, doctors restaurants, gyms, auto dealers, and sales teams that perform product demos. I believe the fastest way for Calendesk to reach millions in annual recurring revenue is to go vertical because that is where there is low competition.

some examples of scheduling software.

1. booxie : is bootstrapped and its revenue is not public. but they raise $1.5 million in 2021.
   2.picktime : can't find out their revenue. but by looking at data from similar web revenue is between $2.0M - $5.0M and 560k total visits traffic.
   3.setmore : $1.9 m in revenue.

4.calendly: more than $143M in revenue.

there is a lot of competition in the market but what I hope one day is products built by indie hackers to reach millions in annual recurring revenue. and I hope Calendesk will reach that.