da fehlt mMn. was. Es heisst sicherlich "...by (on?) his lonesome self."

Aber richtig übersetzt: ganz alleine

on ...(or) by ...

@w: bei Benutzung von "on" müsste es allerdings "...on his own" heissen, nicht "on his (lonesome) self." Und einfach "...by his lonesome" macht auch wenig Sinn.

“But he made it all by his lonesome”.

AE

@w: bist Du Dir da sicher? "Lonesome" ist einfach ein Adjektiv, das fehlt das "self." Man sagt ja auch nicht "by my happy," sondern "by my happy self."

lone·some(lnsm)
adj.
1.
a. Dejected because of a lack of companionship. See Synonyms at alone.
b. Producing such dejection: a lonesome hour at the bar.
2. Deserted; unfrequented: a lonesome valley.
3. Solitary; lone: a lonesome pine.
n. Informal

Self: He ate the meal all by his lonesome.

s.o.

w: thank you, I learned something new. I've only heard that phrase in connection with "self." One never ceases to learn!:-)