Every three years latest models come on the market, and the old ones become obsolete. The company stops updating the software to its older models. People still go for those outdated smartphones at a lower price because they buy them to show their status to others. Who knows that they purchased it after the new one was released? As far as the buyers of the latest smartphones, they need the updates of the software daily to cope with their job requirements, etc. Though their old smartphones have become obsolete, every aspect of the old one is available in the new one.