How to convince my wife for not keeping a relationship with other guys because we have a child

Be patient till your little girl is grown up, Only a perfect relationship between parents mould child to be a good person.

Convince your wife to stay with in the relationship atleast for her daughter.

Make her understand what are the pros and cons if she is out of the relationship. Ask her to think about her daughter's future. Ask her to imagine a little girl's life(the struggle she faces) either with only mother or father.

You try to be more friendly with your wife, make sure that she changes her mind set towards you.

Hope everything will be fine as time passes.
As a startup entrepreneur, is it a waste of time to study philosophy?

First I should say that I'm a serial entrepreneur just embarking on my 4th startup.  The first three have varied from moderately successful to what might be considered very successful. In my experience it's been ideal to have both technical study (focusing on

Can calisthenics be done every day?

Yes you can.If you have done some training before, you could easily have a daily session and not have any aches and pains for the next day.At least not so much that you can't train.Doing this will teach you to recover faster,

Why are people abusive? (apart from being abused before)

The nature of man is a universal mystery.People chase power. When they are too silly or too unpleasant to earn it, they sometimes take it.Like the drug dealer buying his flashy car with criminal gains. They don't want to work or cannot achieve in the real world, yet want the rewards. (power/money.respect)