There is an additional factor you need to bear in mind.
I am an older pilot currently doing CPL prior to proceeding on to do an FI rating with a view to becoming a club instructor as my ultimate end.
Some of the FTOs I have spoken to have said to me (without any prompting on my part) that they prefer people who are going to become career instructors to those who are merely building hours toward an airline job.
The reason is quite simple. At least a small proportion of hours builders, who have presented themselves for instructing jobs, have proven to be largely uninterested either in instructing or in their students. This has been off-putting for the students and hence bad for business.
In happier times, when instructors were not two a penny, FTOs were grateful to have hours builders. Now, however, they can afford to be picky.