Reasons For Y2k to scare the bejeezus out of you...

1. You may not be able to access your bank account, you effectively might lose access to your own money.
2. Automobiles and trucks, or any other mechanized equipment may not start. You can't get to work, get to the hospital, visit relatives, or do anything else requiring the use of a vehicle.
3. Your pacemaker, or the pacemaker of your parents, neighbors, or friends may cease to work. Many may die.
4. Your electricity may go off, and stay off for a very long time. You'd have no way to run your furnace without electricity, so you may get very cold. No electric lights to see by at night, no electric stove or microwave cooking. Your freezers could thaw everything out. Even more serious, nuclear power plants might experience enough problems to cause nuclear meltdowns.
5. Your government checks may not arrive, the only cash you would have would be what you had on hand.
6. Your creditors may think you are extremely behind on your bills, as they wouldn't show your having made any payments on your accounts.
7. Your credit and debit cards might not work anymore, so you wouldn't be able to buy anything on credit, or get any cash at ATM machines.
8. Airplanes may not operate at all, and if they can, they may not be able to receive take off and landing instructions, or know the proximity of other planes in the air. This would affect commercial, private, and military aircraft.
9. Possibly no weather monitoring would be possible, leaving us unaware of pending storms, or other dangerous conditions.
10. Hospital equipment might malfunction, give inaccurate readings, and otherwise put patients lives in danger.
11. Anti-Nuclear monitoring equipment might also malfunction, by either shutting down completely, or more seriously, give false information that might trigger nuclear war.
12. The stock markets around the world could potentially collapse, especially if sales and statistical information were to be inaccurately reported. The companies themselves might see the value of their stocks decline if their operations became impeded, affected in some way by Y2K.
13. Mass unemployment might result, if company operations were no longer sustainable.
14. If cars, trucks, trains, airplanes couldn't run, the transportation system would fail, which would cause massive shortages of food and water. There would be undelivered equipment, including much needed medicine, and anything else that current relied on shipping.
15. Such immense unemployment, shortages of food, water, medicines, coupled with the lack of availability of money, and the shutdown of the transportation system, could cause widespread panic. Civil disobedience would become rampant. Personal safety would become a thing of the past, as law enforcement officials, as well as all government personnel would have to vacate their jobs in the interest of endeavoring to protect their own families.

Reservoir Tip / Jason Bright