Not true. Assuming that your pools has a 0% margin, you have a maximum of 340 ADA to give away, but only when your pool actually makes a block. Under no circumstances can this double the delegator reward unless you reach deep into your own pockets. If you have more than one 250k customer, you will still only have 340 p.e. to distribute among all.
The model is fundamentally flawed - others may call it a scam because there is no conceivable way that it can hold it’s promises. Perhaps you like to have a look at this post - it compares operator cost vs. just delegate.