Given that Henry IV had i) half the de Bohun lands plus the incredibly vast Lancastrian inheritance, plus all the crown lands that Richard II had enjoyed, ii) the proceeds of 'treason' that were significant even after he had doled our relief to widows and dependants, iii) the contents of a well-stocked treasury including vast amounts of gold stacked up in Holt Castle - it seems incredible that within a very short time he did not have the proverbial pot. His subjects were bewildered, and it's one of the reasons he became so remarkably unpopular in fairly short order.
So what went wrong?
1.) He picked a number of officers who, if not actually inept, were certainly very far from being ept. These were largely former Lancastrian retinue people with no prior knowledge of running a government and its finances. (c.f Richard III and his use of northerners he could trust. Henry did the same sort of thing eighty years earlier.) It took him years to get the right men into place.
2.) Probably to seem as different from Richard II as possible, he started wars on several fronts. Scotland was invaded early in the reign, and thereafter was a running sore. Wales rose under Owain Glyndwr, and kept on rising until after Henry's death. Ireland continued in chaos - no great change there, but it still needed treasure, blood and toil. Fighting with France and Brittany, much of it unofficial, much at sea, became endemic.
3.) He personally retained vast numbers of men - as mentioned in an earlier post, he was soon spending more on his retinue than Richard II. (However this was not a Bad Thing, apparently, as historians never criticise this spending, though they give Richard hell for spending a lesser sum on his personal retainers.)
4.) He gave a ridiculously large dower to his wife, Joanna of Navarre.
5.) He faced a regular programme of domestic uprisings, right through to 1408. Considering what a lousy king Richard II was supposed to be, and how unpopular, it's amazing how many people (ranging from ploughman to princess, pauper to prelate) were willing to risk their lives and property to avenge his memory. Had Henry died at Shrewsbury in 1403 (as he very nearly did) one wonders what history would have said about him. Tyrant and regicide perhaps? Maybe Shakespeare would have given him a hunchback.
Financial crisis was to become the leitmotif of the Lancastrian dynasty - they were never able to square the circle of an ambitious foreign policy and an inadequate financial base. Private individuals may have grown rich on the French wars of Henry V and Henry VI, but for the national treasury, and for taxpayers, these wars were a disaster. It was no plucking of roses in a garden that brought down the dynasty, nor yet the ambitions of Richard of York and Richard Neville. It was the 15th century credit crunch, with its roots in the dire financial management of Henry Bolingbroke's government.