True - especially as their 'good causes' category is vaguely broad.
However, they don't advertise by telling potential participants tha the money for charity is 'the best part' - they know that most people only want to win the money!
If that were your main impetus and you didn't primarily have a big hope for personal gain in mind, why wouldn't you just give X amount to your favourite charity and gift aid it, rather than playing the lottery so that somebody else's choice of charities could get a very much smaller amount of your 'donation'?!