出典:Wiktionary
The phrase may have originally been used to qualify a statement of advice, opinion, or suggestion by referring to such a statement and describing it separately from making it.
"For what it's worth" can be used to emphasize humility by prompting the reader/listener to provide their judgment of worth against the statement being made; i.e., it may be useful information, it may not be, or perhaps differs from that the recipient's opinion.
to value the established worth of something
価値あるもの
the value of doing something
the real value of something or someone
something of little worth
something that is worth speaking of
the actual value
半額で
for half the price