But seriously what are negative impact on massive stimulus?
Seriously, no one really knows.
But ... we can have an educated guess.
However, this time, just my opinion, a lot of contradictory evidence.
1) History shows that printing money leads to the debasement of the currency, that is exemplified by the wheel barrel full of money. If this is the key currency, usually that means the key currency will be replaced by another currency.
2) However, it appears we live in deflationary times. Do not expect inflation to be automatic. There is inflation in asset prices, but not much anywhere else.
3) The US debt is held in US dollars, so they can inflate their debt away. Whether that collapses their currency is a very curious question.
This part is unknown, that is what will other countries do? Remember the history of the Great Depression, it was all about competitive devaluations of a nation's currency, the beggar thy neighbour policy everyone did.
Suppose, the Americans start printing money more aggressively to pay down the debt, putting a lot of pressure on the USD to go down, like what President Trump wanted. How would the Euro and RMB react, what would the authorities behind the Euro and RMB do? Let the Americans devalue how much they want to devalue the USD, or they will act and let their Euro and RMB drop too?
This part, we really do not know. Logically, if all paper money becoming worthless, hard assets will go up and up and up, like gold. At any rate, everyone should own some gold in these times. Like that guy Jim Rogers said, he was a peasant and peasant like to own some gold. Hard assets would be real estate, or anything material they say.
That is the most important part. Protect yourself, save your own ass. No one will do it for you. A diversified portfolio of stocks and hard assets probably is the best way to go.
4) The next crisis is unpredictable. I really believe in chaos theory. 2008 and 2020 where just random events, where everything just happened just that way. However, in the history of financial crises, they tend to be spread out a little more, such as 10 years then 10 years another crisis. Next crisis could wipe out the US Dollar. Who knows, protect yourself.