When you give too much, people become accustomed to it, building up a tolerance. You are a generous person, so they react less ecstatically to your kindness as they are less impressed.
While this is normal, the people-pleaser is addicted to the reaction and must always give more to get the same response until it looks like insanity: your excessive kindness is overbearing and self-destructive.
The addictive nature of the diminishing high leads to a vicious cycle.
From Nick Pollard