We have been building large traffic and content solutions on top of WordPress for years. WordPress will excel both in your initial phase, saving time and costs for building a decent solution, and your growth scaling. Some of the largest news websites are built on top of WordPress, since it started as a blogging platform.

Example lists:

http://vip.wordpress.com/clients/
http://www.wpbeginner.com/showcase/40-most-notable-big-name-brands-that-are-using-wordpress/

WordPress is popular enough to support a large number of services out of the box (with plugins).

There are plenty of managed WordPress hosting solutions such as SiteGround that are optimized for WordPress projects, caching plugins like WP Rocket or W3 Total Cache that do most of the heavy-lifting if you want to skip the optimization until you become profitable.

You can also find various security extensions for two-factor authentication, file monitoring, or other goodies - as well as integration to CDNs and software firewalls.

Schedule a call and I'll help you plan your strategy, avoid obstacles and grow with time.