K as used in your example is commonly used regarding denominations as an abbreviation for kilo which represents the 1,000 multiple of a unit. Therefore it would not be incorrect to abbreviate $2,000 by using 2k which means 2 x 1,000. M is the roman numeral for 1,000. Roman numerals do not go beyond 1,000.
What happens after 10k followers on Instagram?
Once you have 10k followers, Instagram will make it easier for you to get people to your website via Stories with the swipe up to link feature. Swipe up is the only way to get a direct link from your Instagram to your other web properties. And, it’s available in STORIES, if you have 10k followers.