He's right if you just look at it today. I only have one Vega56, but after adjusting the hashrate for my miner's fee and the pool fee, I get a net 2094 h/s on Monero for 185W at the wall (it averages a little over 2160 h/s before accounting for fees) . That's currently $1.44/day - (185W/1000*24*$0.10) = $0.99/day net profit. Of course, it takes a little more knowledge and effort to set up a Vega56 than an Nvidia card and a couple months ago it was barely breaking even while a lot of NVidia cards were still making decent profits (e.g. At one point, my GTX 1060s were making $0.25+ per day on Grin while my Vega 56 was making $0.01 on Monero), but at least that's some info to plug into a spreadsheet for people to analyze on their own.
This is why I do a spreadsheets... I don't agree with your math.
A Vega56 costs $270 plus tax and shipping where I am in the U.S. But let just say it's $270 all in. (This is confirmed by PCPartsPicker.com). Then you look up Whattomine.com and the top coin for this GPU, as I type this, is Monero. Vega56 earns 1.20 less .51 for electric equals $.69 profit a day. Maybe you do a little better and earn 5% more, call it $.73 a day. That equals an ROI of about 370 days. Not bad, but in the same range as the best Nvidia mining cards. Basically the market stays in some type of floating balance where miners float to the best profits over time.
There are a lot of variables - are you a Spec Miner or a Cash Miner or a Hybrid of the two. What coins/protocols do you believe are worth mining/holding. How much are you investing. There are lots of drivers. Every miner has a different path, that doesn't make them right or wrong, just different strokes for different folks.
You do you and good luck.