In 2014, the 61-year-old star was left terrified after a mentally unwell stalker broke into her house while she was there, and she is still affected by the incident more than a decade later.
"It makes me think: do I really have to go outside and navigate the world?" she told Vanity Fair magazine.
"There's the cases where they got into the house, the cases where they're outside the house, the cases where you're on a film set and they figured out where you are, and the cases that no one hears about.
"It's ongoing. It's not a one-off. And it does create a mindset where your home also unfortunately becomes your fortress."
Bullock's close friend Jennifer Aniston was at home in May when a 48-year-old man - who has been accused of stalking, which he has denied - allegedly drove into her gate.
"People are out of their minds. Who wants to put that energy out there," the Friends actor said.
She said her security team was "not glamorous in any way", instead describing it as "a necessity".
Bullock said the two friends encouraged each other to leave the comfort of their own homes.
"There's a motivation of going, 'OK, we need to go somewhere. Where are we going?'" she said.
"I'm desperately trying not to Howard Hughes myself," Aniston joked.
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