Why hackers want to get into your computer, mobile device

• Clients are always tell me I don't need antivirus software? (Especially, Mac, FYI YTD Macs has 2209 vulnerabilities vs Windows at 900)
• I have nothing to hide on computer or mobile device? 
• So why do hackers want to hack my computer so badly? 

This is the same argument used by anti-vaccinators, I don't need it, I never get sick, I am strong enough. 

Well you maybe the unwitting the carrier of this virus, and the spreader of the disease to your closes family and friends. Now you have become the infection. And most likely you won't even know it, because symptoms are not showing. Active carriers who do not present signs or symptoms of disease despite infection are called asymptomatic carriers, in medical parlance.

In computer parlance, asymptomatic carriers are called zombies. 

Most of the times hackers want, you personal information, but there's another reason. They want to be able to control your computer to do things. Get enough of them together, and you can carry out attacks. An army of zombie computers can be used in DDos attacks. DDos attacks is basically flooding a service or website at the same time with millions of request, overloading that sevice or site. Each zombie computer has to come from somewhere, and guess what if you don't have antivirus you are one of them. Mac users!

Here's a real world consequence of your zombie machine; 

From SlashDot, takedown of Telegram via a DDos Attack to prevent Hong Kong protest for continued freedoms!

The distributed denial of service attack that hit Telegram Wednesday came from China, the secure messaging app's founder said. Pavel Durov's tweet suggested that the country's government may have done it to disrupt protests in Hong Kong. From a report:In a DDoS attack, an online service gets bombarded with traffic from networks of bots, to the point where it's overwhelmed and legit users get frozen out. In an explanation Wednesday, Telegram compared it to an "army of lemmings" jumping the line at a McDonald's and making innumerable "garbage requests." Durov said, "IP addresses coming mostly from China. Historically, all state actor-sized DDoS (200-400 Gb/s of junk) we experienced coincided in time with protests in Hong Kong (coordinated on Telegram). This case was not an exception." Tens of thousands took to Hong Kong's streets to oppose a government plan that'd allow extraditions to mainland China. People are worried that it would bring the semiautonomous former British colony under the Chinese government's thumb. These protesters relied on encrypted messaging services, which let them mask their identities from Chinese authorities, to communicate.