Yes, that is true. A year ago my friend mined (with one RIG, five GPUs) almost 30 Ethereum per month and in June 2017. he got less than 2. At the other side, price increased so he earns now more than in July 2016.

If you want to invest first of all you have to ask yourself how much can I invest in hardware. Than you have to choose which one is the best (as you can see these new GPUs do not have the best price-earning ratios). Than put all information in calculator

1. https://www.cryptocompare.com/mining/calculator/eth?HashingPower=20&HashingUnit=MH%2Fs&PowerConsumption=140&CostPerkWh=0.12
2. https://whattomine.com/
   At the end you will know is it profitable.

If you have more questions I will be glad to answer it.