So afaics the only reason the USA supports Israel is the lobby. What else could it be?
I think there are a lot of complex reasons for it. It would be wrong to say the lobby isn't a factor to some extent, but it is also wrong to say it is the main one, and even more wrong wrong to say it is the only one.
Firstly, Israel is considered to be a dependable ally in a volatile region. The US was an ally of Saddam Hussein's oil rich Iraq during their war with Iran, but then they invaded oil rich US ally Kuwait - it is hardly straightforward to say "just ally with the Arabs."
And if they weren't US allies, they would probably be Russian allies instead which would change the nature of the region in ways detrimental to the US.
Secondly, the role of the holocaust in western historical imagination has made criticism of Israel more complicated and difficult than it would otherwise be.
Thirdly, Israel has an important theological role in the imagination of evangelicals and therefore broader US political culture.
Related to this is a fourth reason - racism. The reality is far more complex and nuanced, but the American right wing basically view the conflict as white "Judeo-Christian" Israelis vs an other of brown Islamic Palestinians. It's a projection and reflection of US domestic racial politics. In fact it is no coincidence that American-Israelis are massively over-represented amongst extremist Israeli settlers (around 15% of settlers are American in origin compared to 2.2% of the Israeli population.)
So yes, the Israeli lobby is a thing, but they operate within a political culture which has other reasons for being pro-Israel, including ideological, cultural and geopolitical reasons.