The Carters are the made-up family in my sample plan. They have $260,000 sitting in cash. Not because they are careless. Because every time they thought about investing it, something in the news said wait.
I do not think cautious people are foolish. Cash never has a bad year, and that feels like safety. This piece is about what that feeling costs.
Cash has a job
Three jobs, actually.
Emergencies. A few months of expenses, so a surprise does not become a debt.
Money you will spend soon. A down payment, tuition, a tax bill. If you need it within a few years, it should not be riding the stock market.
Sleep. Some people need more of a cushion to stay calm. That is a real need, not a weakness.
If your cash is doing one of those jobs, it is not “too much.” Too much is whatever is left over, sitting there with no job at all.
What idle cash costs
There are two costs, and neither one shows up on a statement.
Prices rise. If prices go up 3% a year, $100,000 buys in twenty years what about $55,000 buys today. The balance looks the same. It just does less.
Growth you never got. This is the bigger one. A finance professor at NYU keeps a table going back to 1928. In it, $100 in short-term Treasury bills grew to about $2,600 by the end of 2025. The same $100 in the S&P 500 grew to about $1.16 million.
That is not a free lunch. By my count from the same table, stocks lost money in 26 of those 98 years. That is the trade. Cash never has a bad year, and it never has a great decade.
Now put the Carters’ number in. Take $260,000 and leave it alone for twenty years. At 3% a year it becomes about $470,000. At 8% it becomes about $1.2 million. The gap is about $740,000. That is an illustration with assumed returns, not a forecast, and the invested path would have dropped hard more than once along the way.
The penalty for safety now is risk later.
The risk later is simple. It is reaching the age when you want to stop working and finding that the money is all there, exactly as you left it, and it is not enough.
Why smart people keep waiting
Because waiting feels like a decision. “I will invest after the drop.” “After the election.” “When things settle.”
Vanguard tested this. Looking at markets from 1976 to 2022, it found that investing a lump sum right away beat spreading it out about two-thirds of the time. And both approaches beat sitting in cash about 70% of the time.
The reason is plain. Markets rise in more years than they fall, so on most days waiting costs you. I wrote about the fear of buying at the top in should you wait for the crash?
But “usually” is not “always.” And a plan you abandon at the first drop is worth nothing.
A calm way to move
First, fence off the cash that has a job. Emergencies and near-term spending stay put. You are only deciding about the rest.
Then pick one of two paths, and write it down. All at once, which the numbers favor. Or in equal parts on fixed dates, say once a month for six months. Spreading it out is the price of sleeping well. Vanguard’s work says it is a small price, and it still beats staying in cash.
Decide in advance what you will do when it drops. Because it will, at some point. A rule written while you are calm holds up better than a choice made in a bad week. That is The Pre-Decision.
Write the fear down, with a date. “I am afraid the market falls 20% right after I invest.” Then check it in ninety days against what happened. That is The Fear Journal, and it is the fastest way I know to learn how often your fears come true.
How much cash is right for you depends on your work, your health and your nerves. I cannot set that from here.
Related questions: is my 401(k) safe in a crash, pay off the mortgage or invest, are target date funds good and advisor or do it yourself.
One question for this week: what job is your cash doing? If the answer is “none,” how long has it been waiting?
As always, if you want to talk any of this through, the door is open. Genti