What are the most common ways people wreck their motorcycles and how badly injured are they?

Two main causes of motorcycle wrecks. 1/ The rider. 2/ Someone else.
Rider caused wrecks are from going too fast and usually involve sliding and stopping when you hit something hard. Like a tree or a wall. Serious injury or death. Or sliding under another vehicle. Death.
Other driver wrecks are when someone pulls out right in front of you so there is nothing you can do and you go straight into the side of the car or truck or get thrown over it. Same result. Serious injury or death.

stupidity, it's just amazing how many ways motor cyclists can be stupid on the road

A seasoned motorcycle rider has a saying that there are only 2 types of motorcycle rides 1 those who have had an accident. And 2 those who are GOING to have an accident, so prepare look in summer how many seasoned motorcycle riders wear leather...all seasoned riders, because road rash is a wicked mistress

Half of all motorcycle accidents happen to riders with less than a year's riding experience. That means (1) Starting out, you should see safety as your first concern and (2) if you're still alive after a year you're already twice as safe! (Personally, I think this statistic is skewed by young guys who just HAVE to learn to ride on a 150hp sportbike.)

A significant percentage of motorcycle accidents involve alcohol. I've heard numbers from 40% to 60%. I'm guessing a lot of that is the biker himself, but some is idiots in cars who 'don't see' the biker.

More than half of motorcycle accidents are 'single-vehicle' accidents. Meaning the biker himself makes a mistake--going into a curve too hot is a major one. The bike goes wide on a curve and takes out a section of fence. If it's a right-hand curve, you can go right under the wheels of oncoming traffic. So a lot of safety has to do with just riding carefully, not speeding or stunting or scraping the footpegs.

After that, cars present a serious hazard. They 'don't see' motorcycles. It's very common for a biker to be killed by a car backing out of a driveway into his path or an oncoming car turning left across his path. The drivers always say 'I didn't see him!' We minimize this by being 'paranoid', keeping our distance from cars, not assuming what they're going to do.

Statistically you are more likely to have an accident per mile on a bike than in a car. And of course when you do the consequences are more severe. About 8% of motorcycle accidents are fatal vs 1% for cars, but the injuries are also much worse.

Most common?

Too much speed for the given scenario.
Alcohol.

Bumps and bruises to fatal.

Every crash is different.

Cars and trucks not seeing them.

they fall .....and yeah they get hurt.

Personally, I think that is their own, because they may racing car, drunk driving. What caused by some reasons, in addition, of course, is also likely to be some of the other changes

Excess speed for the conditions.

trying to out drive your skill level, driving in bad weather, not paying attention. injuries could be anything from cuts and bruises to getting killed.

i think the most common would have to be slipping out like when its raining. or hitting pot holes... mostly nothing to bad

Under estimating the power and acceleration capabilities of a sportbike.
Gunning the throttle after leaving a parking lot and have the bike slide out from under them.
Bruised ego with minor road rash.
Approx $500 in cosmetic damage to their bike.