If you're like, well, almost everybody, you're not saving enough. 15% of each paycheck into the 401(k) is the bare minimum you can get away with
If I were to channel my inner David Graeber, I would say that if you save more, then someone else has to go into debt more. After all, how can you obtain a promise to future consumption without someone else making such a promise?
Saving is a positive-sum game when it finances capital formation. Otherwise, it may be more of a zero-sum game, in which people with one set of values accumulate wealth while people with another set of values squander wealth. Hence the term "Vicky," from Neal Stephenson's The Diamond Age.
It gets worse. The Vickies are going to end up with a rising share of income, and the Thetes (the squanderers) are going to end up with a falling share of income. Cries of "Fight Inequality!" will echo throughout the land. Scott Sumner's pleas to focus on consumption rather than income will go unheeded.
It gets worse still. The ultimate squanderers are politicians, who squander other people's money. Under the banner of "Fight Inequality!" they will squander even more.
This leads to a different version of the paradox of thrift. The more that the Vickies save, the more the politicians squander. Overall net saving and capital formation fall.