Yeah, you're right, that is the reason. I've been working full time for the site for over a month now and get to spend a few hours a day swatting bots. A lot of tools we've put in help but just manually checking the accounts they flag usually leads me to thousands more.
Yip, just strange that the bots can have a upside too, because the higher the Lotto jackpot is, the more money will flow into it from people who are seeing the massive carrot.

We are 1 day and 8 hours from the draw and the Jackpot is only at 0.28 BTC, where it was at 2.6 BTC a few weeks ago.
Oh, well.. The advantages of not having bots might outweigh the disadvantage of not having that big carrot.

Well I would not call it an advantage cause the bots participating also decrease the chances of ll honest users to win.
In fact they would be an advantage if accounts flagged as bots woulb not be allowed to win the lottery as it was proposed several times.
One could for exmple just rise the nonce of the lottery drawing by 1 if a bot accound was selected to win although this causes problems if the bot detection system flags a dedicated real user.