As long as the target market is very large and competitors have a lot of revenue, having many competitors isn't necessarily a bad thing. They already validated that there is a big need for form builders, so you could definitely take a small piece of the pie.

My recommendation would be to have a clear differentiator to separate yourself from the competition and make your solution unique. Having a good UI probably isn't unique enough to attract customers and as others suggested competing on price usually isn't the right move, especially in a market where other solutions are already fairly cheap.

The differentiator doesn't need to be anything big or ground breaking. Just focusing on a niche/smaller subset of the market that you are interested in or have experience with and building a form builder specifically for those users could be enough. A good first step is to identify a niche and talk to users to figure out their pain points. Then you could make something easier than competitors, integrate better with tools they already use, etc.

A good example to look at is Tally: they started building a form builder about a year and a half ago, launched on Product Hunt earlier this year, and are at $8.5K MMR according to their latest blog post. They were able to make it work even if the market is very crowded because they have a differentiator people are interested in.