Ha, look at all the digital-age youngsters that scoff at the pleasure of owning physical stuff.
Going all digital on books, movies and photos is like not having them to me. I have a few photo albums that I've looked at dozens of time in my life. I also have some GBs of digital photos that I barely remember shooting, and never go out of my way to look at. Digital hoarding is much harder to sort, as you barely know what's in that folder, and it takes no time to transfer a bunch of files to an external hard drive you'll never access except to dump some more files every once in a while.
And books, my God. When I was younger, books were my lifeblood. Any excuse was good to buy a book. First time my parents took me to America, all I cared about was books. I came home with a bag full of books. You'd always see me with a book by my side.
In the last few years I've done some cleaning, but it's safe to say that if I didn't have all the paper I have, my house would be practically empty. But my heart would be, too. When I go to other people's houses I wonder how they can have a messy house when there's barely a single book in sight. What can you possibly fill the space with if you don't have books?
I do have a Kindle, but a physical book is something else.
I can share a bit the regret of people like DirtyLarry here, but in the end, I don't understand how you can actually feel guilty for getting stuff that pleased you. When you earn some good money and have disposable income, it's perfectly normal to spend it. You can't save forever and never enjoy the money. What's a lot of saved money for? Stuff or vacations or travel, you'd have spent that money anyway, because that's what money is for. Very few stuff in life is essential, and our lives are full of superfluous stuff. How big is your TV? Did you ever think that a smaller one could have done the same? Heck, why have a TV at all? And why have an expensive phone when a cheaper one could do most of the same things? And what about food and drinks? How much of that do you really need, and how much of what you eat and drink is actually garbage with zero nutritional value? And what about your house?
You don't know what's going to happen a few years from now. Having that kind of regret for having enjoyed your money isn't healthy.
Myself, I'll always regret a lot of the stuff I asked my parents when I was a kid and they paid for everything. Toys I barely touched. Video games I wanted and never even played. Books I've still to read. It's hard to repay your parents for what they did for you, and I'll always be at least a little ashamed for the money I made them waste for my whims. So I guess a good lesson to learn here is, teach kids the value of money. But don't regret enjoying your hard-earned money, unless you blew it on alcohol, drugs, or other objectively useless and harmful stuff.