Why did Odysseus pretend to be Helen's suitor if he wanted to win Penelope?

Question

An important point in the story of the Iliad is that Odysseus (hoping to win the hand of Penelope, King Tyndareus niece), proposes an "Oath of Tyndareus", which binds all the suitors of Helen to join one another if one of the suitors abducts her after she marries one.

That Oath was what provided the legal pretext for the whole of Trojan expedition.

It also provided the reason for Odysseus to be sent to Troy (resulting in both the fall of Troy and the "Odyssey"), for he was one of the suitors of Helen! (and he clearly had no wish to go, as evidenced by attempt to fake insanity when summoned).

If Odyssey actually wanted to marry Penelope and not Helen, why was he even among the suitors of Helen in the first place?

First, it seemed entirely useless to him. He could have proposed the Oath without being a Suitor.

Second, that roped him into the whole adventure, and he should have been wily enough to realize it was the risk.

Answer 1

Odysseus was interested in marrying Helen, but he knew he wasn't a favourite amongst the suitors, and had anticipated that Helen would pick Menelaus, if given the choice:

And from Ithaca the sacred might of Odysseus, Laertes son, who knew many-fashioned wiles, sought her to wife. He never sent gifts for the sake of the neat-ankled maid, for he knew in his heart that golden-haired Menelaus would win, since he was greatest of the Achaeans in possessions and was ever sending messages to horse-taming Castor and prize-winning Polydeuces.

_{Source: Hesiod, Catalogue of Women}

Not wanting to leave Sparta empty handed, Odysseus devised the Oath which allowed Helen to choose her favourite, and him to marry Penelope. At this point in time, the Oath was a pretty smart plan; all major players got what they wanted, without conflict. Of course the plan wasn't foolproof and it did backfire eventually, but we can't really blame Odysseus for failing to predict Paris would cross paths with Helen a decade later.

Lastly, I think it's interesting to note that the Oath's actual power is questionable:

And to me it seemeth that Agamemnon got together that fleet, not so much for that he had with him the suitors of Helen bound thereto by oath to Tindareus as for this, that he exceeded the rest in power.

_{Source: Thucydides, History of the Peloponnesian War, Book 1, chapter 9}

Odysseus probably wouldn't have a choice, even if he wasn't bound by the Oath. It wasn't only the suitors that followed Agamemnon after all, the prime example of a non suitor that made it to Troy being Achilles.