Illegitimate companies and scammers have a simple objective. They're after your information in order to get your money. It's much more common for internet scammers to target hundreds of people for small sums rather than a single person for thousands. This is because demanding large sums for a product that is somewhat unclear is an obvious red flag to most.
Survey Junkie makes it quick and easy to jump into the survey game. According to their websites, they say they are the most popular spot online to earn cash and rewards for sharing your thoughts, while that might not be technically true, they are one of the largest survey sites out there. They were launched all the way back in 2005 (which is pretty old for a survey site) and they have over 4,000,000 members.