Not all investments can go to zero... can an investment in an snp500 index fund go to zero? Im not asking if something is theoretically possible but probable I’m asking for personal experience with bond etf investing, which it is apparent you have none. Run along.
As if capital preservation doesn't matter to older wealthy bond investors...sure, just tell your friend that you've asked some basic questions on an internet forum (some of which could have been answered by common sense) and his multi-million dollar investment in high yield junk bonds probably won't go to zero so he has almost nothing to worry about. Btw, even if you did not read the prospectus, why not pull up a chart and look at what happened to some of these bond ETFs back in 2008 / 2009. Along with the yield, that will give you some idea of the level of risk involved.