user17082: As far as I know, most Theravada followers practice according to the Pali Canon even though they accept the Bodhisattva vehicle as well. So, the main focus is to attain Arahantship for most people. My question is: How common is it for Theravada practitioners to aspire to be Buddhas? 

user17097: The difference between Arhantship and Buddha is that the Buddha rediscovers the meditative technique through his/her own effort (rediscovers the technique since the technique is lost as it has been a long time since the last Buddha) that leads to liberation while the arhat learns the technique through Buddha or a line of teachers that have preserved the technique in its purity since the last Buddha. They both are enlightened beings.
I cannot say if it is common or uncommon to aspire to be a Buddha. To aspire for liberation is certainly a commmon goal.  

user8157: In Theravada, the word 'Bodhisatta' refers to an unenlightened person seeking Buddhahood. 
In other words, a Bodhisattva is not a Buddha in Theravada. 

Bhikkhus, before my enlightenment, while I was still only an
  unenlightened Bodhisatta... 
MN 19

This is why most Theravada reject the Mahayana doctrine of Bodhisattva Vehicle and this is why there are two separate doctrines (Theravada & Mahayana) which despise each other. Theravada views the Mahayana doctrine as superstition and Mahayana views the Theravada doctrine as "hina", which means "inferior, low; poor, miserable; vile, base, abject, contemptible, despicable". 

Also, in Theravada, a Buddha is an Arahant but an Arahant is generally not regarded to be a Buddha. Therefore, Theravadans generally aim for Arahant and keep the name 'Buddha' reserved for Gotama Buddha. 

user111: There are many who aspire to be Buddhas even in the Theravada community. But it is not something that is usually encouraged. It is left up to the individual choice. 
Those who make such aspirations out of ego and lack of understanding of the enormity of the task are discouraged and adviced to give it up. Those who  have mastered the Tipitaka at the highest level and proven their worthiness to the community are given blessings. Even then it's not sure until they actually get the blessings of another Sammasambuddha. And it's not certain if they ever get the chance to meet another Buddha, let alone getting the blessing. Those who never get that blessing end up being Pacceka-Buddhas after a long time, if they don't give up the pursuit. 

17082: <p>As far as I know, most Theravada followers practice according to the Pali Canon even though they accept the Bodhisattva vehicle as well. So, the main focus is to attain Arahantship for most people. My question is: How common is it for Theravada practitioners to aspire to be Buddhas? </p>
 17097: <p>The difference between Arhantship and Buddha is that the Buddha rediscovers the meditative technique through his/her own effort (rediscovers the technique since the technique is lost as it has been a long time since the last Buddha) that leads to liberation while the arhat learns the technique through Buddha or a line of teachers that have preserved the technique in its purity since the last Buddha. They both are enlightened beings.</p>

<p>I cannot say if it is common or uncommon to aspire to be a Buddha. To aspire for liberation is certainly a commmon goal.  </p>
 8157: <p>In Theravada, the word 'Bodhisatta' refers to an unenlightened person seeking Buddhahood. </p>

<p>In other words, a Bodhisattva is not a Buddha in Theravada. </p>

<blockquote>
  <p>Bhikkhus, before my enlightenment, while I was still only an
  unenlightened Bodhisatta... </p>
  
  <p><a href="https://suttacentral.net/mn19/en/bodhi" rel="nofollow noreferrer">MN 19</a></p>
</blockquote>

<p>This is why most Theravada reject the Mahayana doctrine of Bodhisattva Vehicle and this is why there are two separate doctrines (Theravada &amp; Mahayana) which despise each other. Theravada views the Mahayana doctrine as superstition and Mahayana views the Theravada doctrine as "<a href="https://suttacentral.net/define/h%C4%ABna" rel="nofollow noreferrer">hina</a>", which means "<em>inferior, low; poor, miserable; vile, base, abject, contemptible, despicable</em>". </p>

<hr>

<p>Also, in Theravada, a Buddha is an Arahant but an Arahant is generally not regarded to be a Buddha. Therefore, Theravadans generally aim for Arahant and keep the name 'Buddha' reserved for Gotama Buddha. </p>
 111: <p>There are many who aspire to be Buddhas even in the Theravada community. But it is not something that is usually encouraged. It is left up to the individual choice. </p>

<p>Those who make such aspirations out of ego and lack of understanding of the enormity of the task are discouraged and adviced to give it up. Those who  have mastered the Tipitaka at the highest level and proven their worthiness to the community are given blessings. Even then it's not sure until they actually get the blessings of another Sammasambuddha. And it's not certain if they ever get the chance to meet another Buddha, let alone getting the blessing. Those who never get that blessing end up being Pacceka-Buddhas after a long time, if they don't give up the pursuit. </p>
