ugh I've been busy, the thread has moved on...
The suggestion of 30% transaction tax on stock sales was deliberately high to intentionally discourage stock sales. Society as a whole doesn't really benefit from high stock volumes. "But liquidity!" you cry... yeah people don't really use stocks for liquidity, they use it for arbitrage and stuff. Perhaps some small portion of stock sales are for liquidity, but the vast majority is for speculation and contributes to systematic issues.
Make it hard to sell stocks and yeah you might have some problems in the system, but you will have gotten rid a huge number of other ways to abuse the system.
It's just not going to work. Shares in the beginning are mainly a way to raise capital to get things off the ground. A 30% share trading tax would basically be the same as outlawing share sales since nobody will take that trade, which would mean no ventures get off the ground with additional funding, which at the end of the day will mean that only the rich can own and run things, and the money stays in families. It would massively curtail social mobility. The next best option would be loans from investor funds, so are you also going to say that the government takes a 30% tax out whenever someone gets a loan, and that you can't refinance a loan without paying another 30% tax on that?
The tax would also be massively unfair. So you buy $1000 worth of shares, but say the government demand %30 tax on top, then the person actually pays $1300 for the shares. Then, say the person decides they need to sells the shares are you going to also charge an entire 30% tax that time too. Great, now you've taxed the person $600 when they didn't actually make any money. Not only won't it work, from any economics standpoint, the idea is nonsensical.
You also need to take into account the alternatives to shares, because all those things are going to be super-attractive to investors with cash once you effectively can't buy shares any more (and nobody is going to buy or sell shares if there's a 30% tax on it, it's just not a thing people have to absorb when it's easily side-stepped). A lot of investors in shares are pension funds, so what you'd be doing is telling pension funds that they can no longer choose that option to invest people's retirement money in. Even if the share market will, in the long term, always turn a profit, nobody's going to want to, or have to, put people's money in that if there's a 30% up front loss. They'll just entirely side-step the entire legislation you've enacted by coming up with new financial instruments that you didn't think of. So you'd have to blanket-tax every conceivable type of transaction 30% to cover your bases. It really doesn't take rocket science to realize that if we implemented a blanket 30% tax on all transactions of all types, which would be needed to avoid loopholes, then the economy would grind to a halt very quickly.
The end result would be massive deflation, which you seem to think is a good thing. But what that would actually mean is that those with liquid wealth would have all the wealth, there would be virtually no transactions or liquid capital available to the regular people, and since because of deflation the value of a dollar has shot to the moon, GDP would crash, while (in real terms) the national debt suddenly inflates times 100. And no, the taxes collected won't pay down the debt. There are less than $2 trillion US dollars in circulation, which is less than 10% of the national debt. Sucking that money out of circulation will cause huge deflation, and since the national debt is pegged to the dollar, then the debt will suddenly balloon out in real terms, so the only people receiving any money will be those holding treasury bonds.