You are not ‘supposed’ to complete it.
I’m level 81 now, it’s my second time doing a pro league and I can only get about 7 stages done (as in destroying the gate)
I’m aware of the fact my skill & understanding of aspects of battling are lacking however I’m content with my current progress as I realise I’m a noob in the learning process.
Of course while leveling up & unlocking new stuff, the player’s perspective of raiding should change.
I can think of a simple example (I still may be wrong in this example, please correct me if I am) : e.g. when your firestorm can reach firebolt towers on the neighbouring lane this spell probably suddenly becomes almost a new spell to you and to the defender. Then you should start thinking in the defender’s shoes. As a defender at that trophy level you’d probably avoid placing FB towers on a straight lane without placing barriers on the other lane to stop one firestorm KO all FB towers (whereas on lower levels you could do that to cover your enemy under fire 100% of the time on the other lane while they deal with snake towers for example… so the dynamics of the game change totally: as a defender you need to re-design the whole base and as an attacker you’ll face more possibilities.
As the defender’s game has changed, so has the attackers, vice versa.
Also, before reaching those high levels, I guess a lot of players would only focus their resources on very few units & spells to enhance the most important part of the game : the offence. However that would mean they (we ) have very limited experience in using the other units & spells hence are only experiencing a limited proportion of the rr2 game.
As a result we are probably reasonably ignorant and inexperienced with a lot of the game play, hence there’s no reason why we would do as well as those rr2 veterans.
in short, don’t be frustrated. Doing pro league while being noobs is like go to an university exam with primary school knowledge. So don’t worry about it, the game still allows you to receive substantial rewards and accumulate them to get strong equipment (pro gears)