[update: I see this argument is raised over and over in other parts of this discussion, I didn't add much]
Wether it's a savings account, a 401k or a revolutionary business idea everything is better for society than your mattress. And people won't invest in anything today when they can invest more tomorrow, but then they'll wait until after tomorrow, or the day after that, or not at all because they reached that time when they eventually have to spend (which would mean they're broke, which is bad).
Inflation is a hidden tax that impacts the poor and middle classes the most. Worse, wealthy people have the means to escape inflation. Today the worlds weathiest simply buy land and property. Is that the sort of “investment” you’re cheering for as a positive result of inflation?
And it's good that you brought up land and property because that's exactly what I don't want people to invest in (unless they actually want to use it for production, like renting it out to people or companies) but housing is something a lot of people do invest in for retirement, especially in my country. I would much rather people invested it in their 401k, a mutual fund, their business idea, bonds or whatever would enable production. Inflation is a tax on people who have money in their mattresses, if you invest money rather than save it you will beat inflation over your life. That's what I want people to be incentivized to do, not to pile them up or freeze them in status symbols like homes.
And inflation can actually help the poor, it makes it much easier for them to pay off their debts as the principal decreases in value. It's the main reason poor farmers fought for bimetalism in Gilded Age America because rich bankers were making a killing on low inflation.
If other people build something or sell something they increase the supply of stuff which makes the prices drop if the currency stays the same. In other words, they're less incentivized to build or sell something (since selling and building has costs) than just keeping the money themselves in their mattress if the amount of currency is fixed.
Why doesn't it lead to a decrease? Well, as soon as the economic output decreases (but the money supply didn't change!), then each dollar is worth less, so the incentive (to not spend because it will be worth more tomorrow) disappears, so the spending starts back up...
A healthy economy requires money to flow through it at a healthy, manageable rate.
To put it short: that people won't have jobs.