.. by being a careful GUI clone of the existing successful product, Lotus 1-2-3. Right down to being largely formula-compatible and having the same hotkeys. That's why F2 is "edit current cell".
The plastic which held them in place was always broken on the school computers :-)
In all seriousness though, I personally owe a great debt to Sophie Wilson et al for building computers and software that made it very easy to start programming the second after turning a computer on; A BASIC interpreter and an Assembler available instantly from ROM. I had endless hours of fun building parallax scrolling star fields by poking directly to video RAM and slowly rendering 3d scenes in Render Bender. It was just a shame that the computers were so expensive.
I spent about a year of savings on my 'beeb' and it was the best money I ever spent. All tricked out it cost as much as a very decent second hand car, a very large amount of money for me back then, I very much recall that I bought the drive enclosure long before I could afford the drives (I basically bought the whole thing piece-by-piece as money became available). Because I couldn't afford the drives I hacked my Sony cassette deck to function as a sort of poor-mans disk drive by connecting the buttons to the user port and the end-of-tape detector to an input pin so I could tell roughly where the head was on the tape. Really slow, especially during on-tape sorting but it worked.
A friend of mine who had rich parents got his + 2 HD drives for his birthday, I had to take the long way around but eventually got there.
Without that machine I'm pretty sure my career would have started 5 years later.
It's the one product by MS that stood out as being best-in-class straight from day one.