President Biden’s budget proposal includes billions of dollars for clean energy, education and child care — ideas being sold for their potential to increase America’s economic potential. One thing it does not include: an outright economic boom.In the assumptions that underpin the administration’s budget, G.D.P. growth is strong in 2021 and 2022 — but strong enough only to return the economy to its prepandemic trend line, not to surge above the trajectory it was on throughout the 2010s.In 2023, G.D.P. growth falls to 2 percent in the budget assumptions, then to 1.8 percent a year through the mid-2020 …
