I can tell you my own experience: 21 years at IBM and at 47 years old I had the opportunity to change. IBM had been good to me but I was getting tired of the big company routine. An owner of a powder coating business offered me a position running the place. Offered to match my current salary.
I went to see my manager at IBM and they offered me $30K in stock options to stay, but I told them I wasn't unhappy and it wasn't about money. I just wanted to try my hand at a small business. They then offered me a 3 year leave of absence, a very generous offer. The leave made my wife feel better as I had a backup plan of sorts, although I knew I'd be sidelining my IBM career long term if I did go back. I did not intend to fail.
The company I joined looked to be growing like crazy, month after month. I'd asked to see the books for the previous year, and while I thought they were carrying a bit too much debt, they'd made money the previous year. Literally a few weeks into the new job I asked to see a current receivables report and was alarmed to see one account, who'd provided 57% of our ytd business, had not made a payment in 3 months and then owed us over $250K. The 'business mgr' who was already upset about me joining, (turns out he'd wanted my job and was resentful of me coming in from the outside) talked down to me about the situation and why there was no need for concern. "This isn't IBM". I made my own arrangements to visit the account a week later.
Came back from a tour of the customer's location, met with our owner and told him there was something wrong at that company; I couldn't put my finger on it, but everyone seemed unsettled and the whole place felt wrong. I'd visited a lot of companies during my IBM time, and had never left one feeling the way I did when I left there. He assured me they'd done business with them for years and he knew the owners personally.
Two weeks later the place was locked up and shut down. Letters went out to companies like ours informing us of what turned out to be a months long, carefully and creatively structured backruptcy, where the owners cashed out a bunch of stuff, walked away and left the creditors holding the debt. Our owner was speechless. I found myself wondering what the heck I'd done to myself by making the career change. My new motto came from Andy Grove at Intel: "Only the paranoid survive"
The next morning all 5 of our mgmt team met. Tough meeeting. The owner was still in shock. I pretty much took over the mtg, telling everyone we'd just learned a painful lesson, failure was not an option and we were going to figure out how the heck to get through this mess. Told the owner to go see the bank and line up short term financing, put our receptionist on the phones doing telemarketing, the entire mgmt team took a 30% pay cut ( we'd created this mess and I wasn't about to start laying off employees because of our ineptness) and two of us started knocking on doors. So much for me running the place; hell, I became a full time sales guy. Lots of long days, sleepless nights. The business mgr was shown the door some weeks later. At one point I prodded him against a wall with my finger, reminding him if he'd been doing his job instead of worrying about mine we might have avoided this mess. Our previous full time sales person (who just didn't get it) was next to go. Sent her out to see a current account to obtain a long overdue price increase and she came back from a $100 steak lunch with a new purchase order at a price lower than what we'd started with. Hired some other people and switched things around.
At the end of my 3 year leave of absence I had to decide which way I was going to go. As you're wondering, being then 50 years old, I faced a big decision; go back to IBM or stay the course? We were still recovering, but I was bull headed enough to not want to walk away, so I formally resigned from IBM, and thanked them for my time there.
We got through it. Years of careful, conservative rebuilding. I never did get my full salary reinstated. I insisted we stay at the reduced rate and introduced performance related bonuses when we were doing better. My wife is still unhappy about that! We didn't starve and I kept a roof over us. I did sell off a few collector cars during the rough times though, to help make ends meet. The company account base is 3 times the size it was, NO ONE ACCOUNT is more than 15-18% of our annual sales and we manage the hell out of receivables. We did not stiff anyone. I know the good Lord was watching over us. I retired 4 years ago now but remain on retainer and stop in a couple mornings a week to help out where I can.
Bottom line, no regrets. Sorry for the long answer to your question. The stress was pretty high, but I got to make my own decisions and knew who to blame if things didn't go right. I sure did learn a lot about cash flow!