The financial industry and elites sucking up all of the capital and holding it, while heavily lobbying to maintain a low-tax environment and to prevent governments from spending on infrastructure and lifestyle improvements for the general population, although they generally are borrowing at near zero or negative interest rates. This results in insufficient demand and secular stagnation. No investment = no growth.

Luxury goods and services are doing well, though.

Also, the United States is not adding jobs at a healthy clip; the jobs are worse and the prime-age (25-54) employment rate has only retraced halfway since the stock crash nearly 10 years ago. The US intentionally pushes a strange number for joblessness that drops people from being counted, and can be adjusted through legislation lengthening and then reducing the period during which unemployment benefits can be collected. The rate jobs are being added would be fine for an economy not recovering from a crash. This is not that economy.

1) 15 years ago marks the crashing of the dotcom bubble, which was used to recover from the recession of the early 90s, which was caused by Reagan ruining the country. So, IMO the way to view it is that Reagan destroys the working class and causes it to live on credit and prayer while cutting infrastructure spending and lowering taxes on the rich. The best thing he does is spend an enormous amount on the military and other welfare for the rich, which creates some sort of replacement demand, although he finances it by driving the national debt into the stratosphere.

2) Clinton deregulates everything, ends welfare as we know it, and encourages a bubble in stocks. A bubble is not a boom - a bubble is a time when people take out loans with collateral that is on fire. During this, he raises taxes, which shifts the Reagan debt to personal debt. The stock bubble crashes as soon as he leaves, and what seemed to be a reasonable amount of debt for the working class to carry became a crushing amount of debt.

3) Then Bush encourages another bubble to save the economy, and it's in houses, an asset that is spread widely among the working class. They mortgage those houses to pay off their debt, and many get to buy some stuff. Bush immediately starts spending again like a maniac in the Reagan model, with an administration consisting largely of exactly the same people: wars on multiple fronts, welfare and tax cuts for the rich, and massive government contracts for insiders.

4) The bubble crashes as Bush leaves, and Obama comes in with a mandate for a massive national veer to the left, wastes most of it on an inadequate healthcare program of right-wing origin that is very nearly a no-op, and in almost every other way is continuity to the Bush administration. He freezes government spending in the lowest interest rate environment in history, and fills the demand hole by handing free money to wealthy people through the bailouts and QE, shifting all of that public debt partially to private working/middle class debt.

5) The rest of that free money has nowhere to go, due to the previously mentioned historically low interest rates, and in addition the tailing off of the marginal return on further investments in technology and industries based on the invention of the transistor, so it ends up in a combination of traditional large industry/natural resource extraction, banks (betting on a repeat of the experience of the bursting of the property bubble, where banks failing from intentionally taking on irrational risk was rewarded by direct, open payments of cash and grants of credit), and tech companies in-name-only, where service companies use the internet in place of phones (as in the original dotcom bubble where they were used in place of mail-order catalogs), or where the actual profits were made in services for B2B, such as advertising or computing infrastructure (the kind of stuff that large industries/finance/fake-tech-companies can park all of their cash in.)

tl;dr it's just kleptocracy.

Majorities of the youth and the marginalized now openly despise government, and have made this election cycle the scariest one we'll see until the midterms which will be the scariest one until the next presidential election. This "low-growth world" is the closest thing we're going to get to a bubble in this financial cycle, since the working/lower-middle classes are seeing absolutely no benefit from QE and the bank bailouts (unlike dotcom and the property bubble.) The only place to fall is open rebellion, tribal violence, and the aimless violence of suicide, mass shootings, and property crime.

/rant (sorry)