In addition to badly throwing the nation into debt, Reagan's tax cut blew out the ceiling on the accumulation of wealth, leading to a new Gilded Age and the rise of a generation of super-wealthy that hadn't been seen since the Robber Baron era of the 1890s or the Roaring 20s.
And, most tragically, Reagan's tax cuts caused America to stop investing in infrastructure. As a nation, we've been coasting since the early 1980s, living on borrowed money while we burn through (in some cases literally) the hospitals, roads, bridges, steam tunnels, and other infrastructure we built in the Golden Age of the Middle Class between the 1940s and the 1980s.
We even stopped investing in the intellectual infrastructure of this nation: college education. A degree that a student in the 1970s could have paid for by working as a waitress at a Howard Johnson's restaurant (what my wife did in the late 60s - I did so working as a near-minimum-wage DJ) now means incurring massive and life-altering debt for all but the very wealthy. Reagan, who as governor ended free tuition at the University of California,
put into place the foundations for the explosion in college tuition we see today.