These platforms are good if you need even some money for bread. However they won’t help you to earn money for normal life. Even in this sphere you can find scammers that would give you work and won’t paid for it, so you’ll lose your time and your money. Anyway it’s better to try than to sit and to do nothing. By the way freelancer sites are better. There you need to do more work but salary is bigger. On freelancer.com I several times found students that where in urgent need of good articles and reports and earned 10-20 dollars at once.