There's no simulator [for Arduino]
The Arduino has an ATmega328P AVR and an ISP connector on it. You can install the (free) Atmel Studio and program it using Atmel or Gnu assembler, and use the Atmel simulator for the chip. Just because it's an Arduino doesn't mean you MUST use the "high level" Arduino IDE and libraries...
Put another way: if you do NOT want to learn the details of microcomputers and electronics, then you have a good reason to get an Arduino.
If you DO want to learn the details, that's not a good reason NOT to buy an Arduino.