One more purpose is not to count. If the strategy looks like some type of martingale, or may be some other but that need to count too - the bot doesn`t mistakes and players can.
I can`t say correctly for what purposes the bots used but i think that there are 2 main ideas: to automate process of gambling and to avoid mistakes.
There are 2 purposes of gamblers using bots that you have mentioned, but the purpose of bots is more focused on automating the gambling process because people can do other activities while the gambling process is running automatically in the background, but many people play manually without using bots because to enjoy the game and analyze opportunities win while playing gambling.