Right - failure can happen, at random, anytime, with any drive. Sad but true. Of course, you could say the same about a car accident - could happen any time. Yet we all drive around as we need to, and for the most part, a majority of the time, we're safe. Same goes for the harddrives...what you see unfortunately when you read 'user reviews' of a product is an inordinate number of highly conflicting reviews - one group says the product is the greatest thing since fire, while the other group says it's a total faulty piece of junk that ruined their life. Take all of that with a grain of salt...think about who generally takes the time to go to a retail website, finds a product they bought, and writes a review about it. Mostly, it's going to be someone who is an extreme fanatic who loves it maybe a little too much, or wants to help that brand...or it's going to be someone who experienced a problem or flaw and is peeved about it. The great masses of buyers in the middle - those perfectly satisfied and fault-free but not particularly fanatical about the product or company - don't bother to write a comment or review. So don't base your decisions too strongly on the comments and user reviews - take them as a small part of your considerations, along with professional tests and reviews, long-term quality reports, your own like of the product design, warranty or the product, and/or any experience you have with the company or product.
That advice goes for almost any product!
For what it's worth, I have had good experiences with two different harddrives so far - I have a Maxtor drive which has been backing up my whole system for 7 years, and I have 3 Western Digital Passport drives that I use for data backups, additional backups, and travel backups all of which have been reliable. I've had two harddrive failures in 18 years between probably 20 total drives, both internal and external included. Both times it was an internal drive that came with the computer - the first time I had no backup, the second time I did. I learned from that first time!