Answer 1

Because a lot of people post spam and offtopic questions, which eventually build up and cost server space.
With free content, the only way to compensate is to add ads.
Thank the spammers and off topic threads :<

https://www.sololearn.com/discuss/1316935/?ref=app

Answer 2

Roko Burilo Yeah I'm an ad hater when it is way overdone.
Many people use this app and challenges are the most done thing here; I believe thats why ads are more existant there.

Youre welcome :)

Answer 3

if you phone/device has a back button. just push that as soon as the ad comes on.
that's what I do.

Answer 4

The ads will help SoloLearn to keep the learning content and all features we have in the app as of now absolutely free. We hope the community will understand the decision which was made to make sure learning content can be provided for free in the future.