The truth is that raising money from shareholders is...

The truth is that raising money from shareholders is documentation intensive and cumbersome and therefore incurs more cost, takes much more time (have to circulate documents for at least a month or so) and the take-up rate is generally really bad whereas doing a placement is quick and can be done in a matter of days. If you are serious about wanting to take part in a capital raising that you think is likely to happen (pretty easy to tell) then call the company and say you want in - most companies will make sure you are included