A $1 upvote can be very lucrative if you're smart with it. Remember your rewards from SP and voting, content creation etc is all free money. The half a million dollars is still in your account and its value will fluctuate with the markets so it could go up or down. Some bots have a total $300+ upvote value which would cost a staggering 150 million approx. I'd love to know how much these whales paid to earn so much wealth because I very much doubt they invested 150 million. More likely they bought a load of steem before launch for a small amount and its value has grown over the years.