Temperature is one of the great killers of laptops. Generally, the insides won't be destroyed until you hit 170F, but the parts will wear out faster at any high temperature. Merely placing some small object under the back of your laptop will raise the bottom off your desk, and that will drop the temperature about 10 degrees. You can buy a cooling fan that sits under your laptop--it will blow cooler air over the bottom, lowering the temperature about ten degrees. (Some critics point out that raising the laptop will accomplish just as much.)
With about 1/6 the inside space of a desktop, a laptop has to struggle to stay cool. Its one exhaust fan is smaller than the exhaust fans on a desktop. Its vents are smaller, and it has less surface area to radiate heat. Start playing high tech games, and you're heading for even more trouble.
But cheap laptops have an advantage over powerful ones. Their CPU (the computer chip) runs at a much lower temperature. With proper care, a cheap laptop can actually last you more than eight years.