Do you really earned so much money at the beginning . For my own experience, I earned between 1$ and 3$ /day.
I had started My adsense on this 15 march and i had earned 48$ So far from my 3 Proxy sites...... Thanks
$75 first month $235 second then I sold my site for $2000 and bought a new one its a month old now and I have made around $200 so far I work 12 hrs a day on them [600 posts in 30 days]
Just focus on adding content and improving profit each month. Decide what your earning goal is......then start a plan to achieve it.