(I didn't mean for this to be so long, sorry!)
I've wanted to homeschool my kids ever since I was a kid. I had a one year homeschooling experience that was wonderful experience, if a bit disorganized. So I plan on being a bit more organized! I don't think that it works for every kid or for every family, but it's something that I feel strongly about for my kids.
I've never really had any interest in home pre-schooling, as I think kids that age are extremely social creatures and grow and learn the best in an atmosphere with other kids their age. I know I'm definitely in the minority about that in this community, but it's just been my experience working with kids in the past, and I think it's proving true for my own kids. It's also a very high-needs age where kids need more "camp counseloring" than they do when they're even a few years older and more independent, and it would be needlessly stressful on me to not get a break, and would definitely decrease the quality of time that we do spend together.
That was my opinion even before I learned more about Montessori and decided to go the Montessori route, but that decision definitely cemented our plan to do preschool. And pushed it to 5 mornings a week, as opposed to just the 3 that she would have done in most of the preschools around here. There are definitely drawbacks to not having any free days with her, but on the other hand she gets so many friggin' vacations I'm not sure we really miss it! It's also been nice to have some alone time with my son.
I know that people homeschool Montessori, and are very happy doing it, but for me personally I think the social aspects of the Montessori classroom are a really, really important part of the philosophy and something that I couldn't replicate at home. So my daughter (and my son to follow) will be doing the 3 year cycle in a Montessori Children's House, and then I plan to pull them after kindergarten and homeschool from there.
So that's my very long answer to your main question. And it is totally and completely 100%ly a "your mileage may vary" thing... this is just where I personally stand. I know that plenty of people do it and are very happy.
As for your fears about not doing a good job, I think those are healthy fears. We're all just sort of making up this whole parenting thing as we go along, and ime being overconfident is just setting yourself up for a fall

Do you have any particular reason why you think you wouldn't be able to successfully homeschool? Or just a general sense that this education SO IMPORTANT and YOUR CHILD'S LIFE AND FUTURE and if you screw up HE WILL NEVER BE ABLE TO GET A JOB etc etc.
If it's the latter, then my suggestion would be to take a deep breath and remember that all journeys start with a single step. If you decide to homeschool, that does not preclude you from sending him to school if it doesn't work out. If you decide to go with a traditional school, that does not preclude you from pulling him out later. If you homeschool and pick a math curriculum that turns out to be a total disaster for your son, and just doesn't mesh with his learning style, there is absolutely no reason why you can't buy another curriculum and catch up within a few months. I think that there are few homeschoolers who don't have experience buying a curriculum of some sort that turned out to not work.
While homeschooling seems like a Very Big Decision, just remember that few things in life are set in stone. And that I think it's normal to look ahead and fret that we might mess up our kids. In retrospect, it's kind of funny how obsessed I was with starting solids. Omg, must start with food A for 3 days, then food B for 3 days, must not be twenty minutes before exactly 6 months of age, have benedryl at the ready in case she's allergic to the avocado!. On the other hand, my son's first experience with solids involved a banana nut muffin that he snatched from my daughter's plate when he was 5 months. There are really bad ways to educate your kids, just like there are really bad ways to feed your kids: rice cereal in the bottle at 3 weeks, vodka and orang juice as a complete breakfast for your 3 year old. But I think that you kind of have to go out of your way to do such a bad job. A little bit of common sense and a little bit of flexibility go a long way.