I am thinking of long term investing into US S&P500. How do I escape 30% witholding tax?

Unfortunately, taxes are dictated by the authorities. I would believe it is impossible to avoid. Even the Ireland Domiciled ETF has withholding, but at a lower rate.

Don't be so affected by the withholding tax. You still get paid dividends, but at a lower rate. And if you are still very concerned about this, go for growth stocks that don't pay dividends. Capital gains are not subject to tax.

There's no way to 'escape' from the withholding taxes, in the sense that you try to evade paying those taxes and get in trouble with the law for doing so.

A legitimate alternative might be to consider investing in Irish domiciled S&P500 ETFs, which has a lower withholding tax of 15% due to the tax treaty between U.S. and Ireland. You can refer to this guide written by Seedly to find out more: https://blog.seedly.sg/how-to-invest-in-ireland...