That graph makes no statement whatsoever about whether real income in the bottom 50% has gone down, stayed flat, or risen over the 30-year period under discussion. For that, you’d look at a real income chart over the 30 year period, which would show that real income has increased over that span.
If incomes at the bottom rise by 20% vs 10% inflation and incomes at the top rise by by 100%, the income at the bottom went up in real terms, though the share of income at the bottom will have gone down.
this is why I think it will be hilarious when the kids start revolting, and burning shit down folks like you will be looking at graphs and going "how can they be upset, look at this graph! these gig economy renters should be jumping up and down with joy according to my statistics...ungrateful bunch!"
Yours as an individual may not have. No one is saying you're ungrateful as an individual when your experience is different to the group's average.