Startup Idea: Free Online Courses Platform

I'm personally a big fan of e-learning platforms and I do like to use them sometimes. I also love the concept of free content where the platform delivers the content for free and generates revenue from alternative sources...

How cool would it be to have a Udemy or Skillshare but free to use for the users? The only thing similar to this that I know is maybe Youtube?! But, I guess that's it...?!

There is a crazy huge market out there... Now more than ever! So I wonder how a project like this could be viable and profitable for everyone involved... I mean, technically speaking this can be done with advertising, but with so many ad-blockers and other limitations can be extremely challenging to do a project like this...

What do you guys think?