but the Reddit account? I don't get how it is profitable for someone to buy the Reddit account since I don't see any means to make money in Reddit, I don't frequent in that message board so I don't know if there is one.

I've tried connecting all replies, namely:
1. Direct selling of a reddit account as well as replied strongly and clearly by kemarit, harizen, crepasta, Potato Chips and yours (You know also the price of a reddit posts and comments)
2. Bounty and advertising as replied by bittraffic, akuser, Potato Chips, bennguyen and Genamant.  

I just want to add and re-arrange some replies.

Reddit is similar to other forum accounts that are worth based on:

• karma score
• age
• subreddit member if the account moderate a big size subreddit (lot of member, similar to a group on other social media

Reddit account as other social media account shall be more worth if they are monetized especially by a mass marketing staff. With appropriate strategy, reddit will generate money.

Other reddit account worth beside above:
1. Direct goods/services selling
2. A place to search for information that is very diverse with a variety of subreddits filled by people who have specific interests according to their respective subreddits. The quality and popularity of an information can be seen from the number of upvotes in a post / comment. For example: https://www.analyticsvidhya.com/blog/2015/08/best-ever-data-science-discussions-reddit/.
3. Services business of Upvote, Downvote and increasing of a reddit account reputation e.g: https://www.soar.sh/reddit-marketing-services. 50 Upvotes ~= US$ 15 (Not recommended)
4. Creation of Bots for Upvote / Downvote / increasing of a reddit account reputation (Not recommended)
5. Providing reddit training especially on reddit marketing strategy by online or offline
6. etc