The most devasting lose I have felt in this game in the past was the lost of my fleet. The need to always be protecting a fleet in order to keep defense and offensive is a challenge by itself. Therefore I have restarted in Moon Game with a different gameplan. Yet I want to talk about some reasons why and why I would not build up a fleet.
The reality is with a large fleet comes a large use of Uranium. Uranium production starts of low and remains the slowest resource to accumulate compare to metal and silicon. Therefore its a con to build large fleets as it automatically means larger consumption of uranium.
Furthermore overnight when a player is sleeping they may wish to protect their assets by flying their fleet between planets and elongating the fly by delaying the flight time. This works until it does not. On occasions when player forgets to fleet save they are left venerable to attackers.
Some new updates in the Hall Of Fame maybe providing us proof of the consequences of not protecting one's fleet at all times.
The lost of a fleet will mean overall points drop and pretty much losses in resources on planet on top the fleet lost. This is a double whammy.
Of course the positive of having a fleet is you are able to attack and beat opponents who do not have sufficient defense to for use in protection. The attacking part is fun as one hunts down prey. In the game it really comes down to hunter hunting preys and hunters more likely comes out on top.
Another positive is building fleets is quicker than upgrades in research and buildings. Thereby quick rise in points help overall ranks. Of course quick builds can come with quick falls if not protected properly.
For my saving enough to level up buildings allows me to at least save for permanent points even if it takes longer to build. In addition build resource buildings help produce more resources to build even more. Somewhat of a positive feedback loop of building that one can not obtain if they focus mainly on building a fleet.