Here is the explanation of one very senior Shaykh ul Hadith
2. And they say that Your rulers are according to your actions and our actions are bad so our rulers are bad too.
Maulana replies "Yes! Your actions are bad. Jihad is also an action. So do jihad and remove these shameless and ghairatless rulers and bring good rulers through sword."
3. Those who are indulged in luxuries are unable to do jihad. In order to do jihad you have to live simple and tough lives.
Now obviously, you can't just pick up guns and revolt against powerful governments if you don't have sufficient numbers and strength. This is what ulema say. However, according to the explanation of this alim above and Maulana Ilyas Ghumman in his book "Jihad fi Sabeelillah aur Us pe Aiterazat ke Jawabaat" it appears that rulers will not be changed by Salahs, Sawms and other good deeds alone. Force will be needed at some time to remove the evil system, install a new system which will produce good leaders.