How can I get more traffic from a profitable source?

In case a specific source reached its maximum optimized bid you can:

Increase the Maximum optimized bid for the specific source in order to increase the maximum bid for this source and expand the range of bids.

Create a new whitelist optimizer campaign with a designated budget for the specific source(s) (in that case the daily budget won’t be the barrier for buying more traffic). Use the action ‘Blacklist source from this campaign.’