I think you are missing the point.  When you joined (and I did) approx 1-2 years ago, difficulty was much lower and no one predicted that ASIC would make the network difficulty increase at such a rate (30% per 10 days at current rate).

We effectively bought a share in a miner, not an income stream, so we are subject to any changes in difficulty! I am in the same boat, I have (at current BTC value) a small fortune outstanding, but I cant say I was misled.  I invested, knowing that if the difficulty went up, it would take longer to get paid out and if it went down (it has before- not often but it has), it would complete quicker.

If you didn't complete your due diligence then you cant blame anyone else for the fact that your returns will be lower than you expected.