Personally I don't believe root canals are safe, dentists can't 100% kill any bacteria inside that tooth, so if bacteria starts to spread and turn into an infection, and make its way up or down (depending on which tooth) your body can't fight the infection as there is no blood / nerve supply to your tooth which is effectively dead, so I understand.
Not had a root canal myself though and seriously would try to avoid them best I can.
Had a couple of botched fillings though, last one I had a tooth filled, then it broke, filled it again, and broke it again, moved to a NHS / private dentist who said he was quite sure he could save it with a root canal and crown but there was so little tooth left that I wasn't going to fork out however many hundreds of pounds it was for both the root canal and crown on a tooth that was almost gone in the first place, I had already spent £130 on having a white filling on it mind, and even then he couldn't give me a 100% gaurantee the procedure would save the tooth, so I had it out, it's the 3rd from the back on the top row, so it's not very easily viewable, and I get a bit of food stuck between every once in a while but it's fine otherwise.
My mother had a root canal and had nothing but issues with it, so ended up having the tooth removed, so I think it does also depend on the person, the tooth and the dentist, and if you can afford to spend X hundreds on a RC and crown if needed and it then needs removing anyway.