Naively one might think that doubling the tax-rate would double the taxation revenue, but this is not so. As the tax-rate increases people just choose not to trade, because it is not worth their while. This is called dead-weight loss. As we introduce a tax and increase it (say from 1% to 2%), taxation revenue increases. But if the tax rates are very high, and they are still increased (say from 90% to 91%) the revenue raised actually goes down, because people 'drop out' of the trading system.
'Dropping out' takes a number of forms - people choose to leave their jobs and draw welfare; people choose to not buy the items which are heavily taxed (such as insurance); people emigrate in search of lower-taxing regions; people choose to work less hours and spend more leisure time; people choose to make things at home (tax-free) instead of buying them.
There is a point on the Laffer curve at which the taxation revenue is maximized. At this point the government actually reduces its revenue either by increasing or decreasing tax-rates.
This is the point which wealthy social democratic governments will approach. They will try to maximize revenue for pork barreling, and an ignorant population will allow them to do it.
The dead-weight losses at the Laffer curve maximum are horrendous, but an ignorant population won't know this, or choose to ignore it - particularly if they perceive that the taxes are being used to narrow the gap between rich and poor.
Once a government has hit the Laffer curve maximum, they cannot raise more revenue for pork barreling. They must either get by with what they have, borrow money, or increase the country's income. Extremely ignorant populations (like those in many South American Countries) will stand by and let their governments borrow money to point of bankruptcy. Slightly more intelligent populations will see the danger of that, and make their governments get by with what they have.
This is future of social democracy. It's not an Orwellian boot stamping on a human face forever, but it's not exactly utopian nirvana either.
An interesting question is what the Laffer peak tax-rate is. Many believe that many countries in Europe (including England) are already there (or even slightly beyond it), others think the taxpayer can be squeezed for another few percent.
See