If someone else has control of your personal computer, then they have access to all your files, money, contacts, pictures, basically everything. Since computers are so much integrated into our day to day activities, it is necessary to keep them safe and secured.
Computers have and continue to play a vital role in our lives.
It made communication easier, entertainment easier, storage easier, brought in a lot of new technology, it even helped humans land on the moon. Computers are now an integral part of the human world and have made our lives easier in many places.