I have about 9 crowns currently, and my wife is a dental assistant with implant and surgery experience. I asked about this one time and got this explanation.

Implants are a highly invasive, long, and expensive process, like over 10k each expensive, and months of procedures and recovery. Granted, usually implants aren't done to healthy teeth, but they usually have to build up the bone material after extracting the tooth and let that heal, drill into the bone and set the post then let that heal, then fit the implant and adjust everything because your teeth have been moving while it's been healing.One of the reasons the dentist doesn't want to just pull a tooth and do an implant is the even when root canaled, that tooth is a better support than the implant post would be, and the implant is a lot more work.

The process of fillings, then crown, then root canal and crown don't usually happen in sequence like that, and if you do preventative maintenance you can keep a tooth with a filling from ever needing to be crowned or root canal'd

You wanna know what's a hell of a lot cheaper and easier than getting any dental work? Flossing and brushing!

I have hated flossing my entire life because it hurts my fingers to wrap the floss enough not to slide, but a couple months back I discovered I could tie a figure 8 knot and make a loop to pull tension on and now find i can't stand the feeling of anything in-between my teeth so I end up flossing after every meal.

Moral of the story is: floss and brush your teeth and you won't need to worry about crowns or implants. Always before bed and especially after anything with sugar or starches