by ghaash
It actually generally isn't worth it to stay in tokyo until the player count is down to 3 or 2. If in a 5 player game every other person just does 1-2 damage to you, you are close to dead on your turn and can and will most likely be killed by the player following your turn.Staying in tokyo with more than 3 players alive should be reserved to special situations in which you can heal up somehow (evolution, card), can take an extra turn (to gain 2x 2VP and do massive attack damage to everyone outside), can mitigate damage completely or partially, or have other options that make your turn in tokyo especially valuable.
Taking a beating from 3+ players for just a normal turn in tokyo is most likely not worth it.
If you want to make struggling to survive in tokyo more appealing, try rewarding vitory points for starting your turn in tokyo equal to the amount of players still in the game. So if you survive the beating of 5 other monsters and still chose to stay in tokyo, you will be rewarded with 6 VP at the start of your turn. This will also "fix" the problem of people not wanting to participate in the battle. Its hard to "stop" players from staying outside of tokyo and just rolling VPs. Once they have the VP lead and everyone sees they can't win by doing some damage each turn, a race of who can roll the most VPs on their turn begins which is (in my eyes) the most boring way to play KoT.