The cost of living is lower, for sure, but 2 or 3 million a year is not terribly much money in Madrid or Barcelona, especially if you want to have a flat on your own and want to have a comfortable life. For Spanish salaries, Madrid and Barcelona do not belong to the cheap cities. After the deduction of taxes and social security such an amount will allow you to make a living, but you won't have much money left.
I would have thought that people with experience in the internet business can make more? This sum is definitely just a fraction of what you can get in other European countries.