While there are plenty of people whose lives have been thrown into chaos by the lockdowns imposed on us in the name of protecting against COVID, the "free money" sent out without a single Republic vote in Congress went to a lot of people who didn't really need it.  The checks amount to Democrats buying votes, so why should they limit the purchase to the truly needy?

A report from Goldman Sachs, which watches financial flows closely, stated (via MarketWatch):

"These payments may be making their way into mutual funds and ETFs, as well as other assets," the Goldman analysts wrote. "All industry categories saw positive net inflows on the week; the largest net purchases as a share of [asssets (sic) under management] were of industrials and telecom.

And in fact, the flows into the financial markets took a huge jump after the checks were mailed out:

Source.

Goldman estimated:

…that net flows into global equity funds hit a nominal record of $68 billion in the week ended March 17, which when scaled to the level of mutual-fund equity assets was the largest since December 2014.

The total amount of stimulus checks distributed by 3/17 was $242 billion, according to Market Watch, so over a quarter (28%) of that amount flowed into financial investments. Of course, there probably were other funds flowing into the markets anyway, but the graph above shows that less than $20 billion had flowed in the week before. So, Goldman Sachs's supposition is probably correct, that a substantial percentage of checks sent out were invested by those lucky enough to receive them.

The regulations stipulated that checks would go out to:

... single adults who reported adjusted gross income of $75,000 or less on their 2019 tax returns a one-time check for $1,200. Married couples who filed jointly will receive $2,400. Families will get an additional $500 for each child under 17. 

Among the affluent, many receive income that does not show up in the adjusted gross income, for example interest on tax free municipal bonds. Or, they enjoy tax shelters from depreciation or other tax code boons. People whose income is primarily from salary do end up with larger adjusted gross incomes than many wealthier people who are able to manage their tax liability with the help of lawyers and accountants.

Hat tip: Ed Lasky.