What are the basic driving factors that force someone to switch his job ? Is it really necessary to switch jobs often ?

If you understood the question- Upgrade.- Switch jurisdiction.- The desire to develop.- The desire to increase income.

There are a  factors forcing someone to change his work as disrespect, need money, ...

Logically, we must change our work to have more experience and know other trades

No it's not necessary it's Better to grow your knowledge in one place and get upgraded but some times the place add nothing to your knowledge  so you decide to leave .

I mean what if I am satisfied with my job somehow ? Should i still switch after a due time ? 

there is no reason to switch the job except for better opportunity if someone switch its job offenly then its his personality fault. that can be overcome by him self. which includes

Lack of confidence,  someone dont know that he is doing write or wrong beacuse if he knows he is doing write and it will lead him to his desired destination he will never switch, sacrificing your rights for others (first think about your self, first you and your family than others), lack of fighting skill for your right (don't hurt others but don't let them others to you, every time be ready to fight for your rights), lack of whisle blowing knowledge if you are right and know some tring to push you out than this procedure and inform to higher managemnt from down to upward one by one if you don't get any reponse