The basic theory is that Boomers largely took every action (or inaction) that benefited them while pushing the cost of that onto future generations. They took more than they gave back, and they did little to leave the world and economy better off than they found it.
More specifically, they graduated college into one of the strongest economic periods in American history. Boomers also needed less education to get higher paying jobs than their children do, and that college education they always told you to get which would somehow, magically, land you that higher paying job cost them a fraction of what it costs their children or grandkids.
Boomers built an economy where the younger generations increasingly need a college education to move into the middle class, or even to simply hold on to the middle-class lifestyle they were born into, but the Boomers who run state legislatures and private universities have collectively pushed the costs of that now-requisite education into the stratosphere, whereas during the Boomers' time, they could largely pay for their tuition with summer jobs and part-time work.
Another difference is that during Boomers' primary work years, one income was sufficient to get a family ahead economically. But marginal federal income-tax rates have fallen steadily, with rare exception, since Boomers entered the labor force; government retirement benefits have proliferated. The result is that at nearly every opportunity, Boomers chose to push the costs of those tax cuts and spending hikes onto future generations.
They will leave the workforce far wealthier than their parents did, with even more government promises awaiting them. Boomers will be the first generation of retirees to fully enjoy the Medicare prescription-drug benefit; because Social Security payouts rise faster than price inflation, they will draw more-generous retirement benefits than their parents did, in real terms--at their children's expense.
Boomers have run up incomes for the very wealthiest Americans, shrunk the middle class, and, via careless borrowing and reckless financial engineering, driven the economy into the worst recession in 80 years. They drove banks from being relatively conservative institutions into high-risk systems which, unsurprisingly, often failed. Their economic "times of plenty" are characterized by dramatic bubbles growing, then bursting. Most recently, it was the housing bubble, where Boomers drove banks (largely led by the Boomer-led and Boomer-friendly politicians Boomers elected) to lend money and extend credit to people (again, Boomers) that they couldn't afford. Those Boomers effectively bit off more than they could chew, which caused the housing bubble to continue to grow out of control until it eventually popped, sending the American (and global) economies into a tailspin. This could have been avoided if Boomers had been able to exercise some degree of restraint and patience, rather than continually opting for a route characterized by instant gratification.
Perhaps most egregiously, the baby boomers, led by boomer-coddling leaders in Washington, are bequeathing a runaway national debt and a gaping federal budget shortfall that their children and grandchildren will have to pay--through higher taxes or reduced benefits, or both--if they don't want the country to go broke. Balancing America's future receipts and obligations would require all taxes to rise by 35 percent, immediately and permanently, and all federal entitlement benefits to decrease by another 35 percent.
So, at the end of the day, Boomers generally grew up in a time of plenty, and in order for the generations that followed to maintain the same economic stature that they were raised in and that Boomers largely enjoyed, younger generations have to pay a dramatically higher cost.
And as much as I absolutely hate Boomers, at some point, I have to say, who can blame them? Sure, they're largely responsible for the disaster younger generations are inheriting, but how many Gen-X or Gen-Y constituents would have said "No thanks" when offered the chance to have something they want now rather than doing the prudent thing and waiting 5 or 10 more years?