They don't take their extra $100K and stick it under a mattress.
Let's say you "invest" in the stock market. Does that actually cause any business to "invest" more? The answer is likely no. It'll drive up the stock prices of the company whose shares you buy, yes, but companies don't tend to make investment decisions based on their share price.
Conversely, companies do make investment decisions based on the demand for their products, so giving money to poor people who immediately spend it is likely to cause more (real world) investment than giving it to rich people who merely "invest" it.
A corporation doesn't need a third factory if no one is buying their products. Because of deflation it may even want to get rid of it's second factory.
“No purchase, only invest!”
At the end of the day the economy only works because it’s extracting profit from consumers, if the profit you’re extracting is money you lent them in the first place...where is the profit coming from? Hence the negative interest rates: you NEED them to take on more debt so they can even buy things from you to begin with. It’s the market itself saying “you need to give them more money”.