  Understanding the nature of energetic particles in the solar atmosphere is
one of the most important outstanding problems in heliophysics.
Flare-accelerated particles compose a huge fraction of the flare energy budget;
they have large influences on how events develop; they are an important source
of high-energy particles found in the heliosphere; and they are the single most
important corollary to other areas of high-energy astrophysics. Despite the
importance of this area of study, this topic has in the past decade received
only a small fraction of the resources necessary for a full investigation. For
example, NASA has selected no new Explorer-class instrument in the past two
decades that is capable of examining this topic. The advances that are
currently being made in understanding flare-accelerated electrons are largely
undertaken with data from EOVSA (NSF), STIX (ESA), and NuSTAR (NASA
Astrophysics). This is despite the inclusion in the previous Heliophysics
decadal survey of the FOXSI concept as part of the SEE2020 mission, and also
despite NASA's having invested heavily in readying the technology for such an
instrument via four flights of the FOXSI sounding rocket experiment. Due to
that investment, the instrumentation stands ready to implement a hard X-ray
mission to investigate flare-accelerated electrons. This white paper describes
the scientific motivation for why this venture should be undertaken soon.
