Let's look back at the Marshal Plan, in a very simplified fashion:
- USA and WWII Nazi Germany were enemies.
- Allied forces (mainly USA, Great Britain and last but not least USSR) won WWII
- Possible excursion: Lend-Lease made USSR a viable ally
- USA provided financial/economical support to post-war Germany
- Germany became an ally
- USSR became a common enemy
Was the Marshal plan a bad investment?
Let's look at Afghanistan as a counter-example, again very simplified:
- USSR entered Afghanistan during Cold War
- USA provided financial/military support to Afghanistan
- Afghanistan forced USSR out
- USA stopped support
- Afghanistan became an "enemy" (well, you can't say that they were anywhere near being an actual threat to the existence) of USA
Would humanitarian aid to Afghanistan have been a good investment?
Do you think (a part of) the amount of money spent to wage war against Afghanistan would've sufficed to make/keep Afghanistan an ally (especially when spent after commonly "defeating" the USSR)?
If history teaches us anything...
Now ask yourself:
- Is supporting Israel in a self-perpetuating conflict a good investment?
- May supporting the other side break the "self-perpetuating" of the conflict and thus end the necessity of financial support be a good investment in the long-term?
- May even the threat of ending the support of Israel break the "self-perpetuating" of the conflict?
Obama seems to have tried the latter (threat to end support of Israel) first and because he was losing his opportunity to act upon that, he executed the other option (supporting PA) in a last moment effort.
Last section was a guess of mine. We won't know Obama's thought process, unless he confides the details to us. The rhetoric questions might be leading and thus convey opinion. However feel free to come to a different conclusion. To do so, I'd advise to read up on the details of
- Marshal Plan,
- The war of Charlie Wilson (movie about US support for Afghanistan, I don't know the name of the political instrument, however the movie is entertaining and educational)
- and UN mandate to foundation of Israel (which AFAIK actually defined a two-state-solution right from the beginning)
For further reading, I'd advise to find out, how much financial/economical support was provided to Russia after the end of cold war.
My conclusion is that giving support to an enemy is the only way a conflict has ever ended.