If I invented the spreadsheet today, of course I would file for a patent.
I can't help feeling bad for VisiCalc, getting killed by Lotus 123, and they in turn by Excel. Similar to Apple (almost) getting killed by the PC (they invented the Personal Computer - even the term was appropriated by their competitor).When you invent something really useful that's never existed before... don't you deserve something awesome in return? But I guess they did make some serious money; and consumers benefited from the better implementations (which is why they switched). Ownership would have prevented this particular progress.
I still feel bad for them though.