When the Egyptian army deposed and arrested Morsi this was a well considered and long prepared step. So it was foolish to expect that army would give in a re-install Morsi - the more so as the Morsi supporters were not in a position to force the army.
So the logical attitude for the Brotherhood would have been to protest loudly while at the same time cooperating with the army to prepare for the next elections. They should be careful not to provide the army with any excuse to delay the promised elections.
Instead the Morsi supporters chose the confrontation. They stressed the legality of Morsi - conveniently forgetting his not so democratic missteps. They waged a media campaign full of lies to instigate their followers against the new government.
MB members have claimed that the army wants to forbid their movement. They forget that you cannot really forbid a popular movement in a democracy. Its voters will just move to another party to further their interests and sooner or later they will be allowed again.
MB members seem to believe that martyrdom will further their cause. They are wrong. First of all the confrontation will kill many Egyptians and cause a lot of damage. But its long term effects may be even worse. It could be an immediate war like in Algeria or a delayed war as we see in the Syrian conflict - that is to a considerable extent the result of the previous uprising in 1982. They are also forgetting that by forcing the Egyptian army to kill many of them they are increasing the threshold for the army to ever again allow the MB to acquire power.