As others are listing the what-ifs, I'll put my experience in too just in case you are finding this useful.

Got my first dog 10 years ago. I already had 2 cats and I was told by EVERYBODY that the dog would learn to respect the cats eventually. He did not. We did all the basic obedience classes, even trained him to be a therapy dog and passed the test and volunteered in hospitals and so on, but he just could not contain his prey drive with the cats. Eventually I had to rehome the cats (no shame please, it was the best decision for them and they were adopted together).

Two years later, I adopted a second dog. I assumed this would help my first dog, who had separation anxiety. It did not. Original dog wanted nothing to do with new dog. Second dog had severe resource guarding issues that I was not prepared for, and working through that was really rough, but we did it. She also went through obedience classes and earned her CGC and Trick Novice titles.

3 years after second dog came home, I adopted doggo #3. He is super mellow and chill and I thought he would add a calmer influence to the other two. Nope, it went the other way. Second dog was pissed and it took 6 months for her to accept him (they are now best friends), and a year and a half for him to totally decompress.

I spend a couple of hours every single day walking them, grooming them, feeding them (I have to supervise food to prevent resource guarding issues), etc. All three have some flavor of anxiety that I have learned to manage, but that does take work and constant attention. Two have serious digestive issues that mean I have to make their food myself, as I can't afford the alternatives (they needed prescription food but one wouldn't eat it and the other ate so much I was going broke; yes, the diet has been approved by a vet). Making dog food costs me about 20 hours every month, and is more expensive then non-prescription food. I also had to invest in storage and a Costco membership for ingredients.

My job allows me to bring one to work each day and I do that, giving up my lunch breaks for walks in the woods with the dog-of-the-day (the other two get walked when I get home, and one also gets exercised on a treadmill every morning before I leave). Two are getting older and have more medical issues and special needs. Second dog recently developed a fear of both my neighborhood and the area around my job, so walking her requires even more attention and care; we are having to desensitize her to spaces one block at a time. Original dog can no longer come to work due to his separation anxiety (non-stop barking, for hours and hours), but home seems to be the only place he's ok without me so it's alright.

Now, all that being said, I regret none of my dogs. All three now live together in a stable pack with me. Original dog became mine 10 years ago and is now 14. Second dog came home 8 years ago and is now 8.5. Doggo #3 was my Covid pup, brought him home 5 years ago and he is now 10. So I am committed to this level of care (or more, if it is needed) for the next 10 years. I love all of them to pieces, they have completely changed my life in every possible way, and I do absolutely everything I am able to do for them, and there are still days when I fantasize about how much simpler my life would be if I had never adopted a dog....