One caller during the radio show asked why Hitler did attack

One caller during the radio show asked why Hitler did attack so many countries. I think this is a crucial question.
He attacked so many countries because he was forced to. It was Churchill who tried to expand the war. Poland was attacked because of border disputes and bad treatment of ethnic Germans in Poland. England and France then declared war on Germany – not the other way round.
After Poland was defeated Hitler offered peace, after France was defeated he offered again peace. And during the whole war tried Hitler behind the scenes to arrange a peaceful settlement with England. Norway was occupied to forestall a British occupation. The German iron ore supply came from Sweden and was shipped over the ice free harbor Narvick in Norway. England planned a blockade and even to occupy Norway (Operartion Wilfred and Plan R 4). Hitler learned too late of this plans but bad weather spoiled the British efforts and by the skin of a teeth the Brits could be chased off.
After Norway was France – who has declared war on Germany – attacked. Not directly because the Maginot defence line was insurmountable. So Wehrmacht circumvented the line via neutral Belgium and the Netherlands.
France also was staging troops near the Belgian border. They had the same idea and didn´t want to attack the German defence line directly (Siegfried line).
From the Italian King who was somehow related with the Belgian monarchy had Hitler the information that Belgium will let pass French troops.
Next target for Churchill to draw into war was Balkan. Hitler tried to stay out from Balkan and let the people there sort out their problems. The Kingdom of Yugoslavia (i.e.Serbia) joined the Tripartite Pact and became an ally. Two days later the government was with help of Britain toppled and the German embassy torched. This led to the Balkan campaign. Furthermore allowed Greece – who needed help against Italy – Britain to bring troops to Greece. This was a danger to the crude oil supply from Romania, another reason which made it inevitable to occupy Balkan.
After Balkan campaign the Germans tried to invade Britain but put the plan on hold as it became clear that Stalin tried to stab Germany in the back during the invasion of Britain. So Hitler ordered a preemptive strike on Soviet Union.
Hitler never intended a war and made more than enough peace offers or disarmament proposals. So Hitler was not an agent of the high finance. Himmler took advantage of the whole situation and expanded his power more and more. He had plans for a Germanic empire and tried to make SS to a state within the state. He put many bugs in Hitlers head like the destruction of Warsaw and other things and it can not be precluded that the occupied territories would have been permanently occupied if Germany had won the war.

Maybe one final note: Hitler blamed the emperor of beeing too passiv and weak. The German Empire had been encircled prior to WW1. France started to build armaments, made a 3 year proscription and the emperor did nothing. The military suggested prior to WW1 a preemptive strike against Serbia and France but the emperor refused this for the sake of peace. (Wilhelm the second was under the influence of a pacifistic lobby group called Liebenberger Kreis headed by Philipp Eulenburg who talked him out of waging preemptive strikes.)
If France had been disarmed in time there would have had been no WW 1.

This is where Hitlers obsession came from always to be the first to strike if it becomes clear that the enemy wants war. He didn t wanted to repeat the same mistakes which the emperor made.