What you aren't looking at are the real costs of biking. You need good gear, from helmet to jacket to boots, the cheaply made stuff will disintegrate, the good stuff will save skin and lives. If you finance a bike you will then have to get Full Coverage on the bike for insurance, an 18 y/o with a Ninja 650R is a prime target for insurance companies to make money off of, and they do! You also have to realize when you have a wreck, and you will, if you can then take care of your mother, you may not be able to walk and take care of yourself, much less anybody else.
I am also an 'Old Soul', but that doesn't stop others on the road doing stupid things that may cause you to wreck, things happen in split seconds on a bike, things have to be instinctive, that takes experience and time.
Your absolute best bet is to give yourself a chance to learn, and practice. Very first thing to do is take a MSF course, they will teach you the basics of street riding, in addition you will get a small discount on insurance for passing the course, you will need that credit! When there ask about gear, and I mean the good stuff. Helmet, boots, gloves, jacket etc. you will need it to survive, and even then many still die, but it helps even the odds. Next buy a good used Ninja 250 to 400cc only! You will have enough problems learning how to deal with things that happen on the street without having to worry about throttle control. Most beginners panic and twist the throttle at the wrong time, too much power makes them lose control. A Ninja 650R is a supersport racing bike, it is NOT for beginners, in fact it is more bike than nearly every rider on the Planet can handle. Have you ever tried to handle a 130 horsepower bike before????? I can tell you it takes YEARS of riding experience to deal with such a beast, and that is not even riding it to it's potential. Believe me, you are NOT ready for something like that, nothing in the dirt riding world can prepare you for such a rampaging beast.
Getting a reasonable used bike will save MUCH on insurance, you should buy one flat out, and then just put Liability insurance on it only, will save a bundle! Plus when the bike goes down, and it will, they always do for beginners, the repairs should not be as much as a brand new Ninja 650. Besides, do you really want your dream machine getting dinged, scratched and cracked turn signals, cracked fairings etc.? Things get expensive real quick. Then after a couple of years of riding, once you have the gear and experience, and a couple of years older, you can move onto a bigger bike, you need the basics first, a smaller bike will help you learn much quicker.
I have been riding for over 25 years in Los Angeles area traffic, desert riding, mountain riding and fighting traffic. Many don't make it, you have to be good and lucky. I currently have 8 motorcycles, 7 of them street bikes, all modified, mostly for performance. I have some real monsters, but I also have had my share of wrecks and have the scars to prove it. Going down at 75mph on a Freeway teaches a person quite a few things about riding. I started on a CB400, and that was great, but then went to a Ninja ZX900 with a stage 3 jet kit and Yoshi pipe WAY too early, and paid for it. It takes experience, and a LOT of practice to get good, you need to give yourself a chance, nobody else out there will, make the right choice, do it right or your Mom may not have a son coming home one day soon.
Good luck, if you need any help about riding, write me at my email addy.l