I won't recommend building on Wordpress for anything big. Security and scalability challenges will be huge. In addition to that, performance is going to drag with Wordpress.
Money is going to change hands on the marketplace and Wordpress is not known for its security. One hack and you will be on your knees.
Scaling might seem easy if you find the right plugins but if you didn't, things will come to a standstill. A lot of customization will mean paying a huge amount for a 'patched-up' solution.
Go for a modern technology. A lot of PHP frameworks will work and the best one right now is Laravel.
If this is a hobby project, go ahead and use Wordpress.
If it is something that you feel strongly about and want to build right, then, go with a better technology.
Drop me an message if you want to connect with a company that can build it right. I don't want to drop links and look spammy. Cheers!