The reason some people get new bows every year is because they can. Can, meaning they know someone where they get them for cost or at a discount. If you buy a $1000 bow for $700 in March of 2018, sell it in Dec of 2018, you might get $600-650 for it depending on brand. If you wait another 6 months, it's worth about 400-450. So some don't mind losing $100 and have the latest and greatest.
I'd imagine some just have the money to burn because bow hunting and archery are two different things. to some it's a year round hobby. To others a bow is just a means to kill a deer. They pick that bow up Sept 1 and put it down Nov 15th, not to be touched for another 10 months. So depending on where you fall in that spectrum, make your own decision that fits you.
I used to buy new every year and most years i'd made money on the bow. I don't do it anymore because i'm too old to care.